8 1/4 Gear Change Question

If you mix rings and pinions from different used sets you are guaranteeing that you will have a noisy rear end. Once a set has developed a wear pattern you can't mix the parts without it making noise.

If you are going to go through all the work to rebuild a rear end I would recommend a new ring and pinion, they are that expensive. You can get a set for well under $200 from Randy's or National.