In 1971, the 12 bolt rear end was no longer available on any Camaro.  Two versions of the 10 bolt were available.  The 8.2" and the 8.5" rear end.  It is easy to tell the difference between the 12 bolt and the 10 bolt rear ends as they had 12 and 10 bolts on the differential cover.  But the two 10 bolt rear ends are the same in that regard.

I found information and this image on the Internet, so of course you can be assured of it's correctness:

It seems that the 1971 Camaro may have either the 8.2 or the 8.5, perhaps to consume the inventory of the 8.2 rear ends.  It appears as though I have the stronger 8.5" 10 bolt (note the ears on the bottom sides of the differential).  The gearing is 4.10:1 and it has a POSI unit (I think the POSI is an aftermarket piece.