66 Dart rear

What type of power does the engine have? What are your intentions for the car? How do you drive?
What rear does it have now? 8 3/4 very strong very expensive use more power to operate. 8 1/4
strong may be difficult to find for A body and changes you to 5x 4/12 bolt pattern uses more power
and heavier than 7 1/4. If you just want to cruise around and not interested in burn outs, either
stay with the 7 1/4 if that whats in there now, you can pick them up for almost nothing.