GM rear diff identification

I have a 10 bolt GM axle in my 31 Model A, would appreciate information on the ratio and year.

Raised letters on the left side of the diff. GM 25, 3725899, K57. On the right side is stamped AB 1114.

Thanking everyone in advance

 

Google?

 

picture?

 

below the reply field is a button that says "go advanced"
click that...

Now on the next screen, click on "manage attachments" below the reply field.
This will give you a pop-up that lets you choose a picture(s) file to attach.

try again.