Some education please. How to tell?

ok thanks, the code is GM318R 34122195 and sorta randomly crooked underneath that is a single 2. Looks like it is a 318?,... Wow, the way this thing ran in a 3k pound car I can't wait to see my 360 in it!!! This would just squeal the tire with a tap on the gas, I was hoping that the locker took a couple feet to lock up but no dice there. 8 3/4 with no lsd is a bummer.