Hello, I set up 8 3/4 rear ends ( as well as dana 60 and most others) here at my shop.
As far as a dealer, forget about that it would never happen. The "techs" they have working at most are at best glorified parts changers and at worst flat rate guys trying to beat the book on every job, quality be damned.
Your best bet is to find an old school hot rod shop that has old guys (real mechanics and craftsmen).
You can also ship everything to me and I can set it up and ship back. I am just in Arkansas so pretty close.
Thanks, Steve