If you're keeping the 4" bolt pattern wheels, you're pretty much looking for a complete A-body 8 3/4. If you're changing to the 4 1/2" bolt pattern, the '73-6 A-body 8 1/4 will bolt in. With either conversion, you'll need the shock plates, to shorten the driveshaft the appropriate amount, and change the wheels. Depending on what you have in the front, you may have to do some converting there too if you want things to match and carry only one spare. Good time to do a disc brake changeover up front too!
