Rear end casting number?

Is there a site that I can go to and find out what vehicle a rearend originally came out of and the gear ratio it came with? Have a chevy rearend and Id like to know what it came out of.

It came apart different than Im used to, there are 4 studs and nuts on the end of the rearend behind the backing plate that hold the axles in instead of the clips on the inside of the housing on the end of the axles.

Any help is appreciated.

Someone here will recognize your parts description -

Assuming GM, Try this:

GM Rear end codes

OR search google for 'rear end codes'.

A good site that has what you need is not always easy to find.

Bert