Nick Micale has a guy right here in town, very close to him in Northwest Phoenix.
Call him, he's a supporting vendor here, number is on his site. ArizonaGN.com
If it's not a GN or Turbo Buick, AZ Performance Transmission in way North West Phoenix always treated me right with good work and low prices.
I don't know any guys in the far East Valley. Maybe BuickMike will chime in here.....