Rear differential

[jonnymel]

I have a 1960 gmc step side it has a 4:10 gear ratio in it . I would like to change the ratio . I’m thinking 3:55 .
Would still like a good start of the line but need a highway gear too.
Also does anyone have a suggestion for a supplier. Don’t want to change the axle just the differential.

[SkinnyG]

Is this the HO32 rear end (removable center section AND removable rear cover)? I don't think you will find -any- gears for it.

[jonnymel]

Ok
Thanks
Obviously I need to identify exactly what I have first. Possibly not as easy as I’d hoped. So what does everyone do ? Drive around with 4:10 gears or is there a rear axle swap that’s relatively simple .
I have a 454 with a 400 turbo 3 speed and I need to improve my highway rpms

[jonnymel]

Hey SkinnyG
I looked at your Apache project.......great job , I love it.

[SkinnyG]

Thanks!

You could swap just about any axle relatively easily. You'd need to weld on axle mounts. 60-62 is a different width than 63+, so even swapping a later axle requires welding mounts. I'd go 63+ 12-bolt or even a Ford 8.8. Keep in mind bolt pattern and such.

You could swap in a 5-speed. Be gentle though, a 454 has a lot of torque.

You could find a 4L80E for the overdrive and get a trans controller for it.

[jbgroby]

I have a '60 with the DANA 44, called Precision Gear and bought a 3.23 (stock was 3.92), I changed all the inner and outer bearings while I was at it too.

[AcampoDave]

I'm thinking going to a 3.55 still isn't a big enough change to get you what you're looking for. I feel a 454 has plenty enough torque that it should still smoke the tire with a 3.08

[vetnat]

If it is an HO32, Yukon has a 3.38 ring and pinion.
https://www.yukongear.com/partslist....nion+Gear+Sets

[jonnymel]

Thanks , I was wondering about that.

[jonnymel]

Thanks everyone for your input .......I really appreciate it.
I think I will go with the 3:38 Yukon Ring and Pinion.
Next question other than a new diff gasket and cover what other parts would I buy as well.
I’m relatively sure nothing has been done to the rear end previously.
I’m a rookie at this. I will purchase parts but have some qualified help for the install.

[SkinnyG]

Oh cool!

I've previously run Yukon gears - they are very good.

[60short]

from my experience / while you are in there ....

The bearings are R1502EL - available from several manufacturers including Timkin and National

The seals are : SKF 18695 - also interchangeable and available from several manufacturers / vendors.

(the best prices I found was on RockAuto, searching by PN).

Somebody else made a good point - above parts are for the Eaton HO 32/33

[61K10]

take a pic of the rear cover and post it. Most GMC's had a Dana rear axle.

[Killer Bee]

lucky you! most of us just tool around in our 4.57s day dreaming about 4:10s

cross your fingers you've got a dana under there and good luck finding a suitable gear swap!