Chevrolet Camaro Forum : “how to find out if a 10 bolt chevy rear end is 7.5 or 8.5”

You can tell if it is an 8.5 corporate rear by the the lugs underneath the Pumpkin.  If you can see 2 larger triangular lugs it is an 8.5.  If you see smaller pointed lugs it is a 7.5.  Sorry I can't be more specific.  If you check google images you will see what I mean.  If you know what vehicle it came out of, you could find out what rear that vehicle came with.  The 8.5 is a good rear, I am putting 560 horsepower through mine and have no problems.