I just talked to suncoast and they still carry the stage 3 and 4There is no more stage 3 or 4 for the kits.
Stage V is a completely new built tranny that you buy as a whole.
You have a 01, which you would need the new Gmax5 Kit.
I have never had the Duramax in there, never had any tranny issues. Several of my close friends have had tranny's serviced and/or built there with great results.Thurston County Transmissions has done SC's I'm pretty sure.
How decent is that sea-tac tranny place?