Other things to check for:
Oval or "stop sign" cover.

If stop sign, its a 10 bolt 7.25, not an 8.25 (also the axle tubes will neck down from 3" into the housing)
Count the turns of the driveshaft, too. The 8.25 could have 2.45, 2.76, or 2.94 gears (if stock). Could also be an f-body unit and have 3.23s.