Thanks Moporridge!

[Txas2step]

Big shoutout to Moporridge( Mike in Baytown ,Tx.)...he donated a complete np435 set up: trans.,bellhousing,complete clutch,flywheel,mounts,floorpan..I mean the whole enchilada!
We met this evening half way between houston and baytown and talked cars and trucks for an hour.Great guy ! I really appreciate his generosity. Trying to decide to drop it in the '61 shorty or the '68 ute. both are a745 3 on tree. Really great people on this forum. Chris.

[JesseD200CSS]

I hear ya on that Chris!! This forum is a great comunity of Sweptliners!! Everyone is willing to help one another! With parts and advise.

[moporridge]

Its amazing that old pieces of metal can unite people all around the world.....that guy from Brazil for instance....very kool looking Mopars down there...Its great to keep them on the road and save parts from going to scrap. This stuff was made to last......from a bygone era that we need to save and bring back ! My 61 is 50 years old and still working hard...I don't believe a 2011 Dodge would last 50 years....plastics in the electronics and interior would break down and crumble...My wife thinks I'm crazy because I told her that my 61 will last me for the rest of my life....Thats what I bought it for :0)

[moporridge]

Chris, if it were me I'd throw that 4 speed behind that 6......the driveshaft will work with no mods.....just slide the front yoke in about 1/2 inch...it still has travel to spare afterward. It would really help use the torque of that 170 /6..especially if you plan on changing the rear axle ratio to a more highway friendly number like 3.23 . The only drawback would be no e-brake without changing to a 65 up rear axle, which you mentioned was something you wanted to do anyhow.
On another note , sounds like you need a A-518 overdrive automatic to put behind that hopped up small block in your 68....I don't know what ratio is in the 68 but you could use the 3.91 out of the 61 with an A- 518 and you'd krapping in high cotton then....

[Txas2step]

Mike, I think you are spot on as to putting the 4spd behind the six. The '68 has a 3:55 behind it.Just need to start collecting parts to make the conversion to auto.Chris.

[Nuthinbutmopar]

If you're going automatic, go with an overdrive A500 or A518. I did the swap last winter and it's been great.

[Txas2step]

What are the donors and year range on the A 500's.Chris.

[Nuthinbutmopar]

I had one on a 92 Dakota 3.9L, so that's what I used. I don't haul anything because of classic insurance, so the lighter duty didn't bother me.

[moporridge]

You can find the A-500's in late 80's Dodge vans..Picka Part....The A-500 is an A-999 with overdrive....they don't hold up that well for high performance use although.. a shift kit and external cooler will probably help with this . The A-518 is the best choice but more expensive.... I'd go with whatever shows up first.....The A-500 does have a lower first gear than the a-518....
You could put the 3.55 behind the /6 4speed combo and use the 3.91 with an overdrive behind the 318....
We'll find a 65 up housing and put the 3.91 from the 61 tapered axle housing into the new 65 housing ...then just swap the complete housing into the 68 ......afterward putting the 68 3.55 housing into the 61......that way you only have to buy one chunk gasket.
Another plus is that since the 68 has a long tailshaft 3 speed...the driveshaft may work well with the swap to an auto....may have to shorten slightly for a 518.....

[Txas2step]

Mike,sounds like a pretty good plan....thanks for the input. Chris.

[soopernaut]

We'll find a 65 up housing and put the 3.91 from the 61 tapered axle housing into the new 65 housing ...then just swap the complete housing into the 68 ......afterward putting the 68 3.55 housing into the 61......that way you only have to buy one chunk gasket.

I don't believe the center sections of a non-taped axle and a tapered axle are interchangeable without machining the axle housing. I just read something about this recently.

[Txas2step]

The tappered axle on the '61 is a 657 w/ 3:91 gears. So the pumpkins don't interchange w/ the flanged axles 8-3/4?

[soopernaut]

It took a while to find this because most information on the 8.75 doesn't mention this. If the early axle had a Sure Grip then it appears you can swap them. If it was an open carrier then no. It appears this was changed for the year 1964 and those would still be the tapered axles.

http://bionicdodge.com/Download/Mopar_8 ... _Guide.PDF

Section 1: Thrust Block Variations
There was a difference in thrust blocks prior to 1964 that make center section
interchange, as well as axle interchange problematic. The thrust block, or "axle shaft
thrust spacer", it thr block that both left and right axles butt up against inside the center
of the differential. Prior to 1964, all open differentials used a thrust block was
approximately 1/8" to 1/4" thicker than units made after 1964. The Sure Grip thrust
block prior to 1964, however, was indentical to all 1964 and later Sure Grips and open
differentials. In 1964, the thrust block width was changed to match the Sure Grip thrust
block width.
This difference in thrust blocks between Sure Grip differentials and open differentials
required that two different axles be produced for each 8-3/4" housing manufactured. This
is true of all 1959-1963 cars with 8-3/4"s.
A 1964 and later differential, or any Sure Grip differential, cannot be used with 1959-
1963 rearends and axles originally equipped with an open differential. The original axles
must be machined or original Sure Grip length axles must be used.
Part II, Section 3 contains housing and axle sizes and part numbers for these early 8-
3/4" rearends.

[moporridge]

This sounds about right because I have put an early 61 3.91 sure grip centersection "Chunk " into a later 68 housing with no problems.
Time to find a 65 up housing for your 61.......I'm sure someone on this site can help with that :0)

I've got a 2.94 chunk from a 67 Belvedere that would be great behind that 4 speed. Like I said before ,I had a 2.76 behind that 4 speed in my 64 which worked out incredibly well with that "Granny " low......which was actually really useful as a 1st gear with that tall of a gear behind it. I could take off in 2nd as well with no problem....

The old Doug Nash 5 speeds were set-up this way with 5th being 1:01....not an overdrive 5th ..........but having an ultra low 3.27 first gear which when combined with a 3.08 or numerically lower ratio worked out basically the same overall as having say a 4.56 with a tall overdrive .

Personally...I like having this set-up rather than an overdrive tranny because your driveshaft speed is much slower with a 3.08 or lower gear, but with the low first you still have plenty of dig from a stop. The best of both worlds.

[Txas2step]

I think if I can find a complete flanged rear end to put behind the '68 318 with an auto (a518) ,I can drop the 3:55 behind the np435 for the '61...that would be the best. Bad part ,i just put new seals and complete brakes behind the '61 tapered axle...good part , the '68 has that work complete also. "61 will be my driver...'68 will be a work in progress.Chris.