Hot Rods help on olds rearend

hey guys,im tryin to see if i can get help on how to find out what kind of rearend is in my altered.plus im trying to see if once i canfind out if maybe someone has a used ring and pinion for it.like about a 4.56.
thanks,
bill

 

What does it look like? Any numbers or markings? Picture will help identify.

 

im in the process of gettin pics of it right now

 

Somewhere here there is a Olds Pontiac rear end thread with lots of good info. Try some of those words on advanced search,****les only.