8 3/4" narrowing - Dimension Help

Cass a.k.a. Dr Diff is a great resource, and a very busy man. Have you considered just ordering the entire rear end from him? I did that on mine and it bolted right in. It showed up on a pallet at a local shipper.

Also, what are your goals with upgrading to an 8 3/4"? Is it just for strength? Are you converting to BBP? Are you converting to disc brakes? Are you trying to run wide rear tires under the fenders? All these decisions can play into what you are trying to achieve.