The Stovebolt Site Forums The Shop Area Driveline Rear end swap for Advanced Design

Apologies if this has been asked and answered a few times already, I did a quick search but came up empty. I’d like to upgrade the rear-end and driveline of my 51 Chevy ½ ton to something with a better highway gear and an open driveline.

I know it’s probably too much to hope for, but are there any direct swap options available? For example there is a 59 Apache being parted out near-by and I’ve seen a few Chev/Pontiac passenger cars in the 1960 to 1970 range come up as well.

If there isn’t a ‘magic bullet’ solution out there is there something that comes close? What should I be keeping my eyes and ears open for?

Thanks

-check the earley 70,s 1/2 ton chevys.i am using a 72 ,works for me,,,

What about changing to 3:55's??

Going to open driveline means you have to change/modify transmission, rear axle, springs, driveshaft.

Are there NOS 3:55s available or would I be looking to get them out of a similarly aged GM passenger car?

I'm a very novice mechanic and while I'm pretty comfortable under the hood the transmission/driveline and re-end are all pretty much a mystery to me.

Are you doing a full swap with a T5 trans or are you able to go from the 3-speed and torque tube into the newer rear-end?

Also, with a 70s rear did you switch to five bolt wheels all around or could you stay with 6 bolt?

There is information "out there" on swapping a torque tube rear end from something like a '48-54 PowerGlide equipped car. From what I remember, it is a pretty straight swap. I might have a text file with the instructions somewhere. That will allow you to keep the torque tube but have a 3.55:1, and stay away from the installation difficulties of swapping the ring and pinion only.

The Powerglide arrived in 1950. It had a 3.55 rear end and 5 wheel-bolt axles. I recall a Tech Article on a Powerglide conversion being "out there" but cannot quickly remember where (Jim Carter, maybe).

The 3.55 ring&pinion swap suggested by SWEET is the closest you will get to a "direct swap" change in the rear-end ratio in a 47-55 1/2 ton GM truck. Many of us with that conversion have no problem cruising all day at 60-65 mph (with a later 235/261).

What size/year engine do you have/want? A 1954-63 235/261 would be the closest to a "direct swap" engine upgrade.

I did a tech tip here years ago on swapping the passenger torque tube rear end, which I did in my 46. But that was over thirty years ago and I'd avoid that now days as there are much better choices which are less work with better results and you get modern brakes. My 46 now runs a '65-'66 pickup rear end not to wide and lots of ratios swap in. I'm running 3:08s now which was super with the 4 speed but now with my T-5 I'd be better off with around a 3:50.

according to the chevy guru in my neihborhood the 72 rear end i have run 3..38s.it is also a bolt in.yes it is 5on5 bolt pattern..

Life is full of “if’s”

IF you have a good condition column shift 3 speed and want to keep it the 3:55 ring and pinion swap may be the answer. Canadian ring gear carriers have a slightly different bolt circle diameter and require some modification which I can help you with if you decided on that route.

IF intending on a T5 OD trans with open rear the old way is to cut off the end of the input shaft and possibly lengthen splines but lately there are a few sources to solve this by means of a spacer/adapter between trans and bellhousing. Here’s some info:

http://hamiltonintakes.com/products/s10-t-5-swap-adapter

http://www.jalopyjournal.com/forum/showthread.php?t=624631

if u want to switch to 5 bolt check this link...

http://www.quickperformance.com/Technical%20Info/sus_measure.htm

The rearend is the one part of these trucks that sucks