8.25 rearend for an A-body?

No, there was never an 8¼" rear axle with small bolt pattern. Big-bolt only, installed in some A-bodies from '73 through '76.
For what it's worth, I believe the big-bolt pattern corresponds to those with front disc brakes, for those years. Drum brakes continued small bolt pattern and 7¼" rear.

- Erik

64 Valiant, 170 3-spd
82 Volvo wagon, 5.0 5-spd :)