ID GM differential casting numbers?

i've got a GM diff it's got 12 bolts on the cover and on the ring gear, i'm having trouble getting axle seals for it becuase i don't know what it came out of.

i can't find anyone who can look up casting numbers, on one side it's got the numnbers 3896839 with N under it and on the other side it's got GM56. is anyone able to tell me what i've got?

 

My guess is a 12 bolt truck.

 

'78 GMC "Jimmy" for one............

 

how do you know it's a jimmy? if so i'm going to get right on looking up the seals with my parts guy. do you have a casting number book?

if your correct thanks,

 

try calling Randys Ring&Pinion you see his adds in the magazines. He helped me

 

Try these sites

http://www.chevy-camaro.com/parts/chevy-camaro-part-codes-axle.htm

http://www.camaros.org/drivetrain.shtml#axle

 

I have Google............ if you're just "looking for parts", the seals and bearings will have part numbers and brand on them. They can always be crossed to the stores vendor numbers.

 

wow now i feel stupid i only searched the numbers through yahoo, yes i am only looking for the seals. the axle seals didn't have any numbers on them and the crush washer is abnormaly long.

the trouble is, i buy parts, don't write down what i've built the car with and after a few years and deployments, tend to forget what i used.

thanks for the help,
Beaver

 

ok the 78 jimmy axle seals don't match up i'm going to try and use the gear dates although i'm not sure if thats even going to work

 

Try running the numbers past a Chevy dealership or a salvage yard that has a Hollander interchange manual...

 

here's some other casting numbers on the top rear driver side reads CON2 lower same side reads K242....i think thats the date code?

here's the ring gear numbers as well 381779 14:43 GM 1172 2
i think that reads as part number, ratio, and cast date?

i've called a few local truck and GM dealers and salvage yards with no luck

 

Can you post a picture [rear cover area and axle seal area]

 

i have another picture in another file somewhere, i can't seem to find it right now

 

I would really need a rear cover shot, but looking at the picture this might have aftermarket ends. are the axles held in with a c clip or is the bearing pressed on the axle

 

c clip, the ends look stock, the other odd part i forgot to add is the driver side axle seal is differant then the pass

 

What axle bolt pattern is it?

5 on 4 3/4" would be from a car.

5 on 5" or 6 lug would be from a truck.

what shape is the cover?

The numbers on the ring and pinion should help narrow it down. I can try looking up some of these numbers when I get home tonight...

 

5 on 5

 

Very interesting,in the past,a repair axle bearing may have been used to deal with a worn bearing surface on the axle.

 

There should be a stamped number on top of the right side axle tube, IIRC. Assuming its readable, thats what you need for identification, not the casting number.


If its actually a Chevy and not BOP, then 5 on 5" should be '73 or newer 1/2 ton full size truck.

 

Could be 65 -73 Impala, they took a larger seal than the mid size car. what is the problem you are having with the seals to big to small ?

 

the ring number should be 3817779, correct?
My Hollander shows this to have been used from '65-81 and maybe newer in Chevy or GMC trucks. The 5 on 5" pattern would suggest '73-up.

Need the stamped code on top of the axle tube to pin it down any better than that.