Chevy and GMC Duramax Diesel Forum banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!

not working

  1. Transmission Shop
    The allison in my fathers 03 duramax is not shifting and as a result it tops out at 20, 40 or 60 mph when it wants to. The truck is completly stock any help would be appreciated.