transmission swap

Engine, transmission, rear-end, driveline, fuel system etc..
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IRISH70
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transmission swap

Post by IRISH70 »

I have a 70 D100.....318 2bbl, 4 speed 435 trans, 3.55:1 differential gears.

The original set up (above) was intended for industrial use. My idea is to replace the transmission with a more favorable unit gears oriented for the highway driving and fuel economy. A professional engineer (experienced with GM parts) I know has done things like this with Chevys. He recommeded something a late Dakota 5 speed, although his knowledge is not about Dodge. His opinion supports my idea; he suggested seeking information and/or specifics from Mopar sources. So there it is! An invitation to feed me any legitimate facts, or document the senselessness of such a swap.

Irish 70
paperchase40@msn.com

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OleRed66
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Re: transmission swap

Post by OleRed66 »

any overdrive will save you in fuel economy as long as your engine is strong enough to run it. It isn't a bad idea to go with a dakota 5 speed, but why not use a full size tranny. They may be the same, I don't know. If I were you, I'd be looking to replace the 2bbl with a 4. Then if you really want to try things out, check out what Mike Holler does with porting at this site: http://www.allpar.com/fix/holler/head-porting.html There are more links at the bottom of his articles for more of his articles. Get a real nice dual exhaust that flows well and has an X-pipe. Long glass packs are the order of the day, long as in greater than 36 inches. They have excellent flow through and less noise. A good set of all-weather radials will improve mileage as long as the pressure is good. 35-40 psi is probably a good choice, more may be better but you may end up wearing your tire worse. I'd keep your rearend the same. That way if you need to pull something, you still have that ratio that works well for pulling. Convert to an electronic ignition. Petronix makes an excellent conversion kit. Use a good grade synthetic oil, like Amsoil. Make sure the tranny and the diff has good lube. There are so many things that can be done to improve your mileage. Good luck and everyone else please feel free to correct me, I could be wrong about some things.

:usa Mitt Romney in '08
1966 Dodge D100 - Ole Red
1993 Jeep Grand Cherokee - The Jeep
1985 Honda Magna - Maggie
2007 Dodge Durango Hemi (wifes) - D
1992 Plymouth Acclaim - Gramma

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Re: transmission swap

Post by Rodger »

Longmont Person

The Dakota/1500 Van & 1500 Ram had the 5 speed behind the 3.9 V6 and the V8's in the same vehicles. The V8 version is said to have an stronger tail-shaft.

The NP435 that you are speaking of, has an quick ratio version of all four gears called the NP445. If you go with this route you will not be changing and working on all related items.

And do the other stuff that makes it run better.

Rodger & Gabby
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Rodger & Gabby Colo Spgs 47 De Soto S-11, Loaded 62 Imperial Crown Cpe w/62 Lic Plates, 63 Le Baron w/63 Lic Plates, 66 Le Baron, 70 W100 SWB Loaded Custom, 70 Overlander-Internatioal Dbl, 77 D Shorty 2 x 4, 360,NP, 12 bolt

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Re: transmission swap

Post by nfury8 »

I have no idea what it would take to swap or how strong it is, but I can give you a
hands on comparision between them.

My 70 Crew is a mechanically beuatiful truck with 54,000 miles of perfect maintence
from the Air Force, and had the NP435 behind a 318. One of the nicest running 318's
I have ever seen also.

My 97 Dakota has 135,000 miles and the 3.9 with a 5 speed, and still has the factory clutch.

The difference is unbeliavable. The Dakota is a dream to shift and drive. The NP435
was a real work out! My arm would be sore everytime I drove it for a day. Also 3rd gear
is along ways over! I was always trying to jam into 3rd where it was on my Dakota,
instead of way over to the right.

One of my tasks during the rebuild is to swap in an A518 in place of the NP435.
If the NP435 would have behaived even half way like the Dakota 5 speed, it would
still be there.

Now with that all said, I don't even dream that the 5 speed in my Dakota is even half
as strong as the NP435. As for economy, I know the Dakota has an over drive,
but that V6, 2 wd, 5 speed just breaks 18 on the highway. Oddly, it can do 16 around
town all day long.

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Re: transmission swap

Post by IRISH70 »

OleRed66.........Some of your suggestions have already been installed on my 70 D100.........Pertronics electronic ignition, dual exhaust including glasspacks (24") soon to be midified to include the equalizer pipe between, new radial tires (rib all weather for steering, directional winter for drivers). The vehicle runs strong with 137K original miles; I see no need to go internal for performance reasons and disrupt the original stock condition at this time, preferring to be conservative in my options. I do agree with using synthetic lubricants in appropriate cases; in this instance, semi-synthetic is my choice for engine; full synthetics for the trans and differential. Thanks for that reminders, appreciate the advice. Gives me food for thought.

nfury8...........the current trans behind my 318 is the NP435, as your crew cab was originally designed. My 318 is a smooth, powerful running unit, good low end power especially in 4th gear, and will run 70 mph consistently.....with ability to pass from that speed just on out-right acceleration. Took it on a round trip Denver to Dallas, averaged 16 mpg. I know the Dakota (A518?) is not the brute of the NP435, and based on your economy statements of your Dakota, I am wondering if I would actually gain anything by such a swap? My NP435 is tight and accurate in shifting; just seems like I could use one more higher gear sometimes. I actually use it as a 3 speed....2,3,4 gears and omit granny 1. Much appreciated your statements and facts.

Rodger (and Gabby)........from Colorado Springs? I am just north of you, not too far away! This is Phil Hurt in Longmont. (MountainMopar) Robin in Lakewood is a personal friend; in fact he is the person responsible for my good fortune of owning this 70 D100, it being essentially green, hence the reference of Irish 70. I appreciate the information on the NP435 and its counterpart the NP455. You might have given me the best answer to my inquiry.......maybe the close ratio of all 4 gears is the answer I need; my economy might not be the most important issue. Can you turn me on to more information and resource to investigate the NP455 trans? Probably the V8 version?? Might even be able to arrange a trip to see you personally!

My direct e-mail is paperchase40@msn.com ; direct reply from anyone is ok

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Re: transmission swap

Post by Jeffc »

To get what your after you really need to do the math.
In most older engines you need to have the engine turning around 2300 to 2500 (low to middle of optimal power band,
2000 to 3000 on stock engines)
to get max fuel econ.
What your using the truck for will also play a part.
To get this @ 70mph, tire/rim size, trans gears and rear end all play......

My 66 with 318 3.55 rear 435 31" tires does ok on the highway and turns around 28K@65mph
but if I used taller rear gears, say 3.23, I would loose some pulling power and may gain some fuel milage
on the highway empty.

My 73 Scamp 225(supsix) 833od 4speed, 3.23 14" rims turns around 2000rpm@70 and is too high geared
to get max ecom, will be changing it to 3.55 gears ASAP (overdrive is 74 over 1.1, so add that to 3.23
and you get a 2.49, way too tall and works the engine way too hard to get good ecom).

If I were to go to a overdrive trans in my truck I would be looking (just off the top of my head)
at something around a 3.90, or a 4.10 rear to go with the overdrive. Using the 74 OD number with the
the 3.90 number that would put you at a OD of around 3.16 (4.10 would give 3.36, very nice for
over all driving with 15" rims).

The main thing is to find a balance between the engine rpms and rear axle output....
http://imageevent.com/jeffc
62 D100 225 3sp lwb
64 D100 A318 727pb custom lwb
66 D100 A318 4sp lwb
68 D100 B383 727 swb
65 Dart GT LA273 2bbl 904
73 Scamp 225 2bbl 4sp od
68 P300 318 727 base Oasis 22' RV
71 for sale D200 318 auto parts truck could be fixed compleat $400
Old iron or no iron!
One size does NOT fit all!

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Re: transmission swap

Post by IRISH70 »

Thanks again, OleRed66.

Sounds like the first necessary business is for me to install a tachometer. Got to find the running RPM range that exists not as currently equipped. Right? Known facts are that this is a NP435 trans, my differential is a 3.55.......as specified on the manufacturer plate. I am running LT235/75R15 on 15-7 aftermarket steel spoke wheels. Vehicle had 31-10.50R15's all the way around, when I got it less the 11' overhead camper that it had.....didn't want the camper. I found the bigger tires front too massive for steering; too much speedometer error for them on the rear.

Right now the LT235/75R15's all the way around are about right. Stock tire was a 7.00-15 bias; the current radial is essentially the same height, but wider in the section width. A check on the speedometer shows the basic accuracy in the speedo with the LT235/75R15 radials, as it runs now. I am pretty confident that size is best for me.

This all began by a question; could be I would be barking up the wrong tree by changing to an OD trans....the Dakota is weaker in construction than the OEM NP435 I now have. Rodger (in Colo. Springs) replied with information on a NP455, which is essentially the same as a NP435 except it has a close range full synchro in all 4 gears, and was designed to go behind some applications of the V8's. Think I will follow his info, since he lives only about 100 miles south of me right down I-25. Would you have any knowledge or input on the NP455 trans?

Sounds like my '70 is currently set up about the same as your '66. Maybe the better way to go would be changing the rear end from 3.55 to 3.23 for higher gearing, but the trade-off would be pulling power and I would still have the same trans that feels short a gear on the top side. Which brings back thoughts of the NP455 trans as the best swap result, or leave things the way they are. As I said, this all began with a question......and good possibility you have given me the answer I need, which is leave well enough alone. I have a local source (a repair shop, Mopar specialty) across the street, where I will bounce the facts you have stated off him for some objectivity. But through guys like you the purpose of the forum has been once again fulfilled. My thanks, and I will render a decision on good thought, no stupid whim!

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Re: transmission swap

Post by MountainMoparRobin »

If you go to Colorado Springs let me know, I may want to go with you! :lol: OK/????? :study

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Re: transmission swap

Post by nfury8 »

With a 235/75-15 tire and a 3.55 gear, you should be at about 2900 rpm when going 70 mph.
3.23 gears would drop you to about 2630 rpm.
A .74 OD and 3.55 would change that to about 2140 rpm.
OD and 4.10 would be 2470 rpm. This seems like the best of all worlds.
Good RPM range and the low gear grunt of 4.10's.

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Re: transmission swap

Post by Rodger »

Hola Gents and Ah Ho Ho Ho

I have an 1970 W100 ( aka PowerWagon ) and an 1978 D100 with the same NP435 Transmission. I noticed the NP445 info in the 1978 Dodge Dealers Truck Brochure that I have. This has been an "seed of information" for about four years now.

The other night I was on the phone with an site member and this subject came up. I confessed to my learned information and the thoughts of swaping the NP435 for an quick ratio NP445. The other member ( Rukus ) was all full of this option that was used on the Dodge Trucks in the 1961-1971 period and also up into the 80's on the D150's to D350's.

This transmission came in the complete truck line with any engine in front of it. But .... it seems the Engine/Transmission Deptment at the Dodge Division liked to use this transmission behind the six's to keep it in the power curve of the six so the driver could make the best of what they had. And that seems to be the clue of where to find them waiting for you ( at the pick & pull's for $75 ).

Even though I have an 4300 pound Vintage RV Travel Trailer to pull, I do not use it every time I drive the truck, sooo, the 1-2-3-4 usage is better than 2 --- 3---- 4. With the NP435 my take off and then shift with another take off is like following an loaded asphalt truck ( go some and then shift for some more go some and etc ).

The other common items on both trucks is the 235 x 75 x 15 tyres and the 3.5 rear axle gears.

The RPM's stated is the average RPM's of the Torque at its best ( my 3.9 in the Dakota was chassis dyno'd at 1200 - 2980 for it's best torque ).

If any of you want to stop by and do some "truck talkin", do it on the 22nd of Dec from 2 Pm until 6 PM. Robin, Corry and several others all know that if you want to spend the night that we have enough room for you and your passenger's. If you do want to stop by on the 22nd, let us know so that my wife can plan accordly.

Rodger & Gabby
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Rodger & Gabby Colo Spgs 47 De Soto S-11, Loaded 62 Imperial Crown Cpe w/62 Lic Plates, 63 Le Baron w/63 Lic Plates, 66 Le Baron, 70 W100 SWB Loaded Custom, 70 Overlander-Internatioal Dbl, 77 D Shorty 2 x 4, 360,NP, 12 bolt

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Re: transmission swap

Post by Jeffc »

nfury8 wrote:With a 235/75-15 tire and a 3.55 gear, you should be at about 2900 rpm when going 70 mph.
3.23 gears would drop you to about 2630 rpm.
A .74 OD and 3.55 would change that to about 2140 rpm.
OD and 4.10 would be 2470 rpm. This seems like the best of all worlds.
Good RPM range and the low gear grunt of 4.10's.
I tend to agree with the above, if your going to leave the 435 (or use any 1 to 1 output trans) I would
be looking at 3.23 rear gears, it gets you close to mid power band. Yes, you will loose some pulling
power but should be very useable still. Otherwise leave the 3.55 and well enough alone....

If you still think OD might be the choice......
Over drive gear set will depend on what gear set the trans uses on the OD application. The gear
below OD will still be 1 to 1 and give you the 'grunt' power when needed. Using above, the 4.10, or 3.90
set would be about as good as it gets....... go to low with the rear gear set and frist
gear may be come un-useable as anything other than granny on a 5 speed OD trans,
however, that may not be such a bad thing in a truck.....

play with the numbers and make a good choice for your use......
everything is a trade off....

I use the 3.55 in my 68 with a 838 727 p235R15-75, it had 2.91 set in it when it came to me, fine on the
open road @70 plus, but sucked fuel around town which is were it gets most of it's use (engine worked too
hard at lower rpms around town in 3rd and I end up running it in 2nd a lot). If I were to take it
to the track a lot I would be droping the gears at least one step to 3.90 or 4.10 since the engine will turn 6000rpm at the top. If I did more Highway driving I would be looking at a 3.23.

I entend to keep my 66 truck as is with it's 3.55 with the 10-31's set since it gets used to haul often but sometimes
gets on the open road with a load and is overall the best for my use....

BTY, years ago I had a 75 Ply Volary 225 1b 833OD 225r14-70 with 3.55, even with a full load in the car, GF and her
2 kids with gear, it would get 26mpg @ 70 on the open road......were I'm headed with my Scamp(without GF included :lol: ).....
http://imageevent.com/jeffc
62 D100 225 3sp lwb
64 D100 A318 727pb custom lwb
66 D100 A318 4sp lwb
68 D100 B383 727 swb
65 Dart GT LA273 2bbl 904
73 Scamp 225 2bbl 4sp od
68 P300 318 727 base Oasis 22' RV
71 for sale D200 318 auto parts truck could be fixed compleat $400
Old iron or no iron!
One size does NOT fit all!

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Re: transmission swap

Post by mopardwh »

OleRed66 wrote: It isn't a bad idea to go with a dakota 5 speed, but why not use a full size tranny. They may be the same, I don't know.
Same drivetrains they put in the Rams. :Thumbsup A good way to go.
Doug

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Re: transmission swap

Post by Tufftruck »

Halo:
My :2cents I have a 71 SWB with a 225 6cyl A-833 OD trans and 3:55's in the rear with 235/75R15 tires. This is not my daily driver but I treat it like it is. Replacing the old 3-speed on the tree was one of the best swaps I have done to this truck. Usually I cruse around town in 1-2-3 and shift into 4th when I am on the open road. It tachs out at about 2000rpm's at 65+ mph in 4th. Or about 2200 at just above 70 mph. For me it works out great, I don't tow a big trailer but I do have a smaller one (5x8) and it does fine loaded even with the back of the bed also loaded. Like last week when I helped out some freinds move. Chasing parts or going to the hardware store or just transportation I really have fun driving it. It feels like shifting a 18 spline Hemi 4-speed with a Hurst super shifter. This combination works out very well for me and If I were to change to taller tires I would think about changing the gears in the rear to something like 3:91's. And when I put in the BIG BLOCK all kinds of things will change.
70 W-200 440 NP435 SWB
71 D-100 225 A-833 SWB
Hawg

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Re: transmission swap

Post by IRISH70 »

Note for tuffstuff.....on his trans swap 3-sp to 4-sp behind his 225 slant-6

My 70 318 is set up the same as your vehicle: Lt235/75R15 tires, 3.55 differential......behind a 4 speed. My 4-speed is the OEM new process trans (NP-435) with the granny low. What trans did you use in your 4-speed conversion, the NP-435 or the NP-445, which has a close ratio synchronized shift. You say you cruise around town using 1, 2, 3 and go to 4 (assume like an OD) on the freeway, so I am assuning your trans is a NP-445. Would be interested in a direct exchange via personal e-mail, mine is paperchase40@msn.com, on the details of your experienced swap.
Last edited by IRISH70 on Mon Dec 10, 2007 4:30 pm, edited 2 times in total.

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Re: transmission swap

Post by IRISH70 »

First, I stand corrected. The new process transmission Rodger mentioned is apparently a NP-445; these came in the full size van with a V-6 or a V-8, years somewhere around the early 80s, from what I could find.

Second, a stroke of luck across the street from where I live. There is a commercial repair shop, but specializing in Mopars, owned and operated by a man totally nuts on Chrysler Products from hotrods and customs to trucks. He has a 4 speed out of an '82 Ram 150 1/2T van; from the impression I get it quite possibly is the NP-445 full synchro/close ratio that Rodger identified as interchangeable with the NP-435 my pickup now has. The only item of consequence/added expense in a conversion might be the drive line. So, tomorrow I have set a time to physically investigate.

I have dispensed with the idea of using a Dakota 5 speed......too many questions in my mind involving parts, expense, etc. Either I modify with a van or car trans of the 80s vintage, or I retain the original and live with it as is. Could not have come to this point, without the facts and comments voiced herein to my initial question. Thanks to all.

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Re: transmission swap

Post by Tufftruck »

IRISH70 wrote:Note for tuffstuff.....on his trans swap 3-sp to 4-sp behind his 225 slant-6

My 70 318 is set up the same as your vehicle: Lt235/75R15 tires, 3.55 differential......behind a 4 speed. My 4-speed is the OEM new process trans (NP-435) with the granny low. What trans did you use in your 4-speed conversion, the NP-435 or the NP-445, which has a close ratio synchronized shift. You say you cruise around town using 1, 2, 3 and go to 4 (assume like an OD) on the freeway, so I am assuning your trans is a NP-445. Would be interested in a direct exchange via personal e-mail, mine is paperchase40@msn.com, on the details of your experienced swap.

Irish70:
The 4-speed that I use in my swap is an A-833 OD trans. Not the NP-445. This does not have the granny first gear. This is an Overdrive trans. I took it out of a 87 D-100 pick up with a 225 6 cyl engine. I took the bell housing, flywheel, clutch fork, drive line, and everything else that I thought I needed to make this swap. Pick-A-Parts for about $60.00 for everything because it was one of those 1/2 price special weekends. All four forward gears are synco and it has an aluminum case. The shifter is a hurst 4-speed shifter that mounts outside on the left side and is set up like a MOPAR MUSCLE car 4-speed, except 4th gear is Overdrive. Third gear is 1 to 1 ratio and that is why I can drive around town in third. This is not the Heavy-duty truck trans, this is more like a med duty that you find in the late 70 to 80's cars, trucks and vans with a six cyl engine and some 318's. It works very well with the combination that I have now. Of course I replaced the clutch, throw out bearing, pilot bushing and had the flywheel resufacecd. It was just a bolt in swap with only having to shorten the drive line to fit properly. Also had to cut a small hole in the floor for the shifter which was not a big thing. I even used the shifter hump from the 87 D-100 but had to trim it quite a bit to make it fit. I put one of those short chrome Hurst shifter handles with a aluminum T-handle on it and by the looks of it, you would think I had a BIG Block in it or something. Until you start it up and here the 6 cyl. But for right now it is a Blast to drive around. Can not go back to the 3 on the tree now.
70 W-200 440 NP435 SWB
71 D-100 225 A-833 SWB
Hawg

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Re: transmission swap

Post by Jeffc »

Might bring up that the frist year that the 833od trans was often a castiron case (1975), years after were all
alum case....
Yes,often found in vans and PU's in those years as well as some cars......
http://imageevent.com/jeffc
62 D100 225 3sp lwb
64 D100 A318 727pb custom lwb
66 D100 A318 4sp lwb
68 D100 B383 727 swb
65 Dart GT LA273 2bbl 904
73 Scamp 225 2bbl 4sp od
68 P300 318 727 base Oasis 22' RV
71 for sale D200 318 auto parts truck could be fixed compleat $400
Old iron or no iron!
One size does NOT fit all!

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Re: transmission swap

Post by cowboy »

the 883 OD only came with the 318 & /6 model's , & most had a mizer decal in the window for the gas mizer deal mopar was going though to help with the gas crunch at that time
:usa
cowboy Alvin Tx
67 w100 318 3spd
2005 Ram 2500 CC Diesel 4x4 lwb
LAND OF THE FREE
BECAUSE OF THE BRAVE

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Re: transmission swap

Post by MountainMoparRobin »

Irish70
is the swap done????
Are you coming to take me for a ride??? :thinking

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Re: transmission swap

Post by IRISH70 »

All the conjecture on this topic, the advice pro and con......very valuable, a very much appreciated discussion on the topic about a month ago......is now really for naught. I made a decision to procede with my projected undertaking, eliminating the NP-435 in favor of a full synchronized NP A-833 OD transmission. By tomorrow it should be finished, ready for factual results of real road conditions. The
job has been all professionally done by a outside source, as the dollars stated below might indicate.

As of now my 1970 D100 sports the following:
Original 318 LA engine, approximately 140k original miles.
New flywheel.
New diaphram clutch assy complete.
A-833 aluminum case 4-speed, technically a 3-speed with OD....whatever you want to call it!
Gear ratios 1st..............3.09:1
2nd.............1.67:1
4th..............1.00:1
OD............... .71:1 Gears 1,2,4 are same as straight 4-speed
where 4th is highest gear @ 1:1; the 3rd
gear internally is substituted with an OD .71:1
gear having higher final ratio. The progressive
H shift pattern is kept in sequence 1,2,4,OD by
a "fooling" sequence of the internal gears, done
externally by the linkage arrangement.
New one-piece driveshaft.... 3" tube (not 2" std?), having only the rear u-joint, front yoke slip-joint.
(eliminated is the carrier bearing, center velocity joint OEM 2 piece stype shaft)
Tires fore and aft are LT235/75R15 radials....rib steering, directional taction rear.
OEM conditions rendered 16.3 mpg average overall for a 1600 mile trip total.
A tacometer is now operational to document RPM statistics.

Conjecture becomes reality, under the conditions described above........a Saturday voyage for shakedown, the begining of recording honest and true results to see how close speculation and satisfaction match. My random estimate was for $1000; when all is done, my physical speending on an as need basis will be between 0 and $50 UNDER the guestimate...........and I think the results i want to achieve will follow in the path I have chose to go.

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