Chevy Differential Identification

[57ToyBox]

Chevy Differential Identification

On my 57 chev panel


How do I get all the particulars on my Dif with pulling it out from under the truck and cracking it open?

[OrrieG]

The attached pic will help you id the type. To determine if it is posi jack up both wheels and turn the passenger side, if drivers turns the same way it is posi if it turns opposite way it is open. Make a mark on the pinion shaft and have a helper turn the passenger tire one full radius while you count the number of times the pinon turns. That will give you an idea of the ratio. If you want more accuracy, turn the wheel 4 full turn, count total number of pinion turns and divide by 4. Common ratios are 2.78, 3.08, 3.54, 3.73, 3.90, 4.11 and 4.56 which would correspond to the number of pinion turns.

[57ToyBox]

Thanks OrrieG
I'll give that a try. To get an opprox ratio.
I took a quick look at it yesterday. I noticed it had a tipical bolt on diff cover but also had a bolt on third member. Was this common on the tri five trucks?

[2tons of fun]

yup, it called and eaton. depnding on the lug count, gvw and size it will be a 033, 052, or 072.

most likely the 033.

[57ToyBox]

Well, I'm another step closer to finding out the details of my diff

It is a 5 lug
and I also can see that it's a 10 bolt
As soon as I can get it out off the hole it's parked in, I want
to jack it up and start counting pinion shaft revaluations.

Thanks for your help 2tons of fun and OrrieG