Clunk, Bang, Pop, Knock, Creak goes the rear

Well start by testing your ball joints for play. Grab them with a pair of channel locks and give them a real good squeeze. If the ball joint some what compresses/moves around when squeezed then they are worn out.

Check your Axles for slop. While the vehicle is on the ground (load on the wheel) lock a set of vice grips onto the axles and check for play. If there is enough then it could certainly cause a bang when starting off.

I’d also inspect your wheel bearings (if you drift much) because its hard on them. Would also make for a pop/bang when starting off and could also play a roll in poor full mileage.