Converting 3/4 ton to half ton

[MoparMike42]

Firtst off I am dealing with an early '65 Sweptline 3/4 ton long bed. I have already switched the front axel over to half ton and I am wondering if there is anything to watch for when switching the rear. I am mainly concered about the driveshaft length and the u-joints matching up. I want to swap to the 8 3/4 axel. Just wondering if anyone has info on this before I dive into the change.

Here's a picture of the Beast

[Mavis13]

Why in gods name would you want to swap from a 3/4 ton truck down to 1/2 ton in the first place?

[712edf]

If the truck you get your rear from is also a long bed just get the shaft too,assuming its still there..Should work unless the trannys are different or the WB is different due to being another model year.

[Hobcobble]

Nice truck. Welcome to the site
Are you planning on keeping the original leaf
springs? Do you have a one or two piece drive
line? Early '65 was a "funny" year for drive lines.
I've seen both.
John

[MoparMike42]

Thanks for your input guys. I will have to look into that 712edf I will have to check on the driveline. If I remember right, it's a one piece. I stayed with the I-beam front and leaf springs. I like the old school look. I would like to convert it to disc in the front. My brother is building a sweptline he cut the frame from a 70's front end with disc brakes and coil springs so it will be nice to compare the ride difference in the two. His user name is 65alive by the way. As for Mavis13 I want to go half ton for the smoother ride I feel like if it were a work truck 3/4 ton would be great but since I am going the hot rod route, I have chosen half ton, which the only real difference is the suspension.

[cowboy]

It's best to change the leef springs as well , your bolt holes are bigger on the 3/4 ton hangers so you'll have to make them work eather change the bushing out or make a sleeve
Dave

[Cageman]

The driveshaft on your truck now will be to short for the 8 3/4, so you need a longer one, and Im not sure on older trucks, I think the dana 60 had a bigger yoke size for the u joints. I know my 70 and 71 trucks, the dana and 8 3/4 have the same size yokes. So you could swap out the yoke on the pinion to a newer one, but it tourqes to somewhere around 300 pounds IIRC, it is one tight nut.

[wideblock]

one thing i noticed in converting my swept trailer from 1/2 ton to 3/4 was not only the spring eye holes are larger on the 3/4 but the rear hanger brackets were in different locations. the location of the 3/4 ton rear hanger bracket was lower on the frame then what it was on the 1/2 ton. im assuming this was to add clearence for larger tires and springs in the fender well. regaurdless both trucks were 1966 long beds, same options on both on the one exception of 3/4 versus 1/2 ton. thinking back it may have been all in the bracket, not the mounting location, but i do remember the 1/2 ton put the spring eye closer to the top of the frame rail "lowering" the stance of the truck. also the 3/4 ton and the 1/2 ton will be a 2 piece shaft if its a 4spd and a 1 piece if it was 3spd or auto. the length will be different between the tonnage even if the trans are the same.

[wide65]

Wanna trade parts? I have a 65 (though late not early) 1/2 ton that I want to make 3/4

[65alive]

Nice truck. It's nice to see some nice vintage sheetmetal going the hotrod route rather than the "my ol' beater route". I had a '65 D200 that I was going to swap to 1/2 ton axles, but I figured it was too much work. Good luck with the project. There are a lot of knowlegdeable guys on the site, so I'm sure you find the info you need.

Oh yeah, one nice thing about the 3/4 ton to 1/2 ton swap is the 8 3/4 axle has a removable third member, so gear swaps are easy.

[MountainMoparRobin]

I can totally understand the conversion, after all its 44 years old, time to retire, if your going to compare ride, it won't be fair, for 65alive is adding alot of money to get his ride and your staying stock, are you open to suggestions to make your I beam perform as good or better than the IFS and not spend 1/2 the money? even if you don't go to disc, you can do power drum and the difference isn't going to be much . Also you can drop your front and rear to where is will be close to the same height as 65alive's and spend 1/4 the money (you can use else where)
Are you two going to do a video of the comparrisons?

[65alive]

I never said there's anything wrong with the straight axle, it just wasn't what I wanted for my '65. It would be interesting to see the ride quality and handling comparison though now that you mention it. The IFS set up corners just like the leaf set up without the sway bar up front, it's still a truck front end after all. I actually like the straight axle set up better for lowering because of the lack of lowering parts for the '72-'93 trucks.

[MBigDaddyM]

Why must so many ask why people are converting down to a half ton, well if you don't plan on towing and the only thing your gonna haul is @#% the extra three lugs and the weight of the Dana are unnecessary. The 8.75 will hold up to 400-500 hp if you get the later model case. As for the difference in U-joint size, you can buy conversion joints that will match up mismatched yokes sizes and if I remember correctly they are good up to 450hp anything over that and the yokes need to be the same size. -BD

[MountainMoparRobin]

I agree also, on the handling comparison, maybe one day on the September get together will set up a coarse for the comparison.

[MoparMike42]

WOW 65alive and MBigDaddyM finally someone who is on the same page as me! I am interested to see the suspension comparison mountainmoparrobin the I beam with the drums and a booster huh? Do you just put a booster on the existing brake master cylinder or do you convert it to a later model brake system? I still think I would like to set up the disc as it is alot cooler looking. thanks for the ongoing input guys!

[MBigDaddyM]

WOW 65alive and MBigDaddyM finally someone who is on the same page as me!

To be fair, I am converting out of necessity, I want IFS, PS, PB, and have acquired the suspension from an 85 Fifth Avenue to do so. Those cars didn't come in 8 lug, once that is in place, the Dana will be replaced with an 8.75. -BD