Rear End ID...no really!
 

Here's a few pics of my rear end...uh, trucks rear end...and I'd like a few expert's advise on manufacture, type and where to locate the ID numbers to help identify/confirm same. I believe it to be an Eaton rear-end based on what I've seen but I'd like some confirmation, additional info, etc...

Re: Rear End ID...no really!
 

That is an Eaton HO32 under a '60-'62. It will most likely have 3.90 gears unless you are one of the lucky few to have the 3.38 gears.

Re: Rear End ID...no really!
 

So is there any way to definitively tell which gear ratio it is without cracking it open?

Re: Rear End ID...no really!
 

raise it, spin the wheels and count the rotation of the drive shaft. Then look it up on the net. It should get you close.

Re: Rear End ID...no really!
 

The 1/2 ton is stamped on the right front carrier flange. It will be two letters followed by 4 numbers. The letters designate the ratio and the numbers are the day and month made. If yours is original it should MA,MB,MC,MD,ME,MF,MG. which are all 3.90.

Re: Rear End ID...no really!
 

Buy a new gasket for the rear cover, remove the cover, change the fluid, count the teeth on the ring gear and the pinion gear, do the math, reseal the rear cover and top it off with fresh fluid. Chances are that fluid is long overdue for a change.

-Brad

Re: Rear End ID...no really!
 

Not to hog up the thread, Hey guys...I have the GM 12 bolt under my 66..Is that 4.11 or was a 3.73 ratio optional???

Re: Rear End ID...no really!
 

3.73 was usually the norm, most spids specified the 4.11, on 66's that is

Re: Rear End ID...no really!
 

Thanks all for the advise...I'll get it cleaned up this weekend and see what the numbers are and go from there.

Re: Rear End ID...no really!
 

This is what I always suggest also when a guy wants to know what gears are in his rear end.

Hey Lyle! I am so glad you wrote this - I’ve been needing to know how to tell if one has the rarer 3:38 gears vs standard 3:90’s. Can you tell me what the letters have to be for a 3:38? Or better yet, do you have a rear ended with 3:38’s in it?
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