The Stovebolt Site Forums The Shop Area Engine Shop Rear End options for 1951 3600 3/4 Ton?

Hello,
Long time reader, first time poster.

I've got a very stock 1951 3600 truck that I've enjoyed driving and working on but would like to get some higher speeds out of. I assumed the options being a 3/4 ton were:

Rear end swap - Pat from Patrick's suggested a 3/4 Ton Ford rear end that's minimal hassle to swap and fits original wheel bolt pattern.

Overdrive transmission swap. ( It's got a 4 speed Muncie on the floor in great condition and I still enjoy double clutching for the original "feel.")

But I'm curious if anyone has found a carrier or ring / pinion setup that would fit so I could truly keep everything looking stock on the outside.

Here's the post that teased me: Kip Bonds' 1941 3/4 Differential Swap

Kip's truck is the lighter duty 6 lug. So that swap really wouldn't apply to you.
There are 4.10 center chunks out there for your rearend, though are more and more difficult to find.
If you're going to swap the whole axle, an 8 lug Dana 60 would be a good choice and are found in Chev/GMC, Ford and Dodge, which all have the same 8 lug pattern. Ring and pinion sets are also readily available. Dodge 3/4 and 1 ton vans usually have nice ratios like 3.54 and a lot have limited slip as well. They are usually about 65" wide at wms. A little wider than your stock axle, but can be made to work. Pre-1974 these axles are usually a bit narrower and closer to your stock width.

I'd look first for the 4.11 gears for your existing rear. They are hard to find and you may quickly give up, but since they are the most stock looking and the easiest swap, I'd at least give it a shot.

After that decide if you'd rather deal with changing rears or changing transmissions.

A downside of changing to the T-5 trans is that it is not a heavy-duty transmission. If you actually load this truck I'd suggest leaning toward the rear axle swap. And if you load it heavily you need to ask if the trade off of more speed for less grunt will work for you.

If shifting a 5-speed sounds better than swapping rears go that way, otherwise look for an 8-lug rear that is real close to the stock width and swap. While you need to make sure tires don't rub and that the rear fits under the spring and frame, and the actual width measurement is not as critical as many other things are.

Thanks Fellas! The hunt is on. :0)

Hi -

The original rearend should be an Eaton HO52. The Eaton HO52 and HO72 rearends were also used in 1967 through 1972 Chevy/GMC 3/4-ton trucks and are a direct swap/interchange. I picked up a 4.10 ratio carrier/rearend by shopping the classifieds at: www.67-72chevytrucks.com .

When I rebuilt my rearend on my '49 Chevy 3600, I found out that the bearing are barrel-shaped and seemed a bit pricey. However, overall, I like the stock appearance of the Eaton HO52 rearend.

Good Luck!
Dan M.

No need to get stuck with the 4.57 or 5.13 rear gears either. 4wd guys would happily take em off your hands.

Fantastic guys! Finding a little more modern vehicle that holds the same carrier is invaluable. You'd think it wouldn't make a huge difference but doing web searches or asking people on the phone brings up a blank silence or search if you use the 1951 Chev 3600 criteria, but saying a '68 Chevy C20 gets a completely different result. :0)

I believe I have the 4.57 gears. What kind of increase in cruising speed could I expect going with 4.10? I consider 45 mph comfortable right now and would be overjoyed to get 55 mph if possible. :0)

Thanks again. What a great reference this place is!

55 should be pretty doable. You may want to use a gear calculator, but I believe at 65mph your engine would be just under 3000rpm, depends on tire size.

The change would be close to 10% or (4.57 - 4.10)/4.57 = 10.28 %. So your RPM would be roughly the same at 50 mph that you now have at 45.

Webster, yep, you could cruise along at 55 mph just fine with the 4.10 and your stock 216 babbitt pounder. I’ve been running that gear for a couple of years now in my other wise stock 1950, 3604 and it’s great. I’ve put about four or five thousand miles on the old gal since I swapped the gear. On the rare occasion where I might need to pass a REAL slow poke I do kick her up to 65 mph but don’t hold it there for very long. I’m able to cruise down the tollway now as long as I make sure I stay in the far right lane.
It’s a straight exchange, just clean things up good, reseal and bolt the new one in.
dg

Thanks Gentlemen.

It's funny how there's pockets of information out there and you can look for months chasing down cold leads, shift a little and run into a whole bunch of people that have already been there / done that. :0)

Yeah Webster, somethin' like fishin' isn't it.
Denny Graham
Sandwich, IL

I have a 1949 4400 with 6.17 gear ratio. Any suggestions for my situation?

Speaking from the perspective of an old dirt track racer who used a lot of those HO72 4.10 gearsets back in the late 1970's (one reason they're so scarce now), the ring gear carrier has a different side spacing, so it must be changed along with the ring and pinion. If you can find the Detroit Locker center section as well as the gears, grab that, too. They're a little noisy in turns, but in a slippery situation, the pulling power is awesome.
Jerry

AlexJ in Virginia helped me change my 1953 3600 from 4.56 to 4.11. Took under two hours. He sometimes has one of the center sections on hand, and has done the swap many times. If he has one, he can ship it at a reasonable price and talk you through it. You might want to PM him. Just a thought.

Harry

I have a chevy 3600 1953, and I want to change the crown and pinion differential to 4.11, to get more speed. They know site online where I can buy them?

I have the same truck as Juan and I have the same question. Where can I find a third member from a 69-71 Chevy pickup? Any suggestions?
Bob

I have an identical truck. sorta. I have a 51 3600 series 3/4 ton. I took the complete differential from a 72 3/4 ton and installed it. 3:55 ratio. it's a bit wider and I had to open up the center bolt holes a bit, but i'm very happy with the result. 70 mph with tall tires and a 235 engine.

Hey Koolkar -- long time, no chat. Hope all is well.

For everybody else, as a reminder/info, Here's the comprehensive Tech Tip on 3/4-ton and 1-ton rear axle upgrades for higher speeds

Oh yeah, the Stovebolt Tech Tips ...

This is one of the best links for finding a pumpkin.

Ownster.com

They throw craigs list, Ebay and a few others in your search results. This is how I found mine.

Also don’t just try to find the pumpkin. Rolling chassis‘ are also a source. Just ask for the pumpkin. That’s what I did. Find someone selling a frame or part of a truck. And don’t let anyone here kid you. They are hard to find unless your in the north.

Don

any 4x4 rear axle off a chevy truck
post 1975