The G solenoid has nothing to do with the 6 speed as the SUNCOAST 5-6 speed kit doesn't use it(but they do use a G solenoid type valve body). The problem is having the 6th gear pipe installed in the valve body which means you have to start with a 04-05 5 speed valve body to be able to install one. Then you have to have the software to command the extra shift of the C2 and C4 clutch pack for 6th gear. ALLISON has the TCM OS, but they won't pass it up and I doubt it is even on there servers for download if you had access to the ALLISON DOC. For an 01-05 to get 6th gear, your only option is the SUNCOATS kit if you want everything to work like stock(some have installed a GEN IV 6 speed TCM and made the other changes, but it still won't work as designed as the GEN IV TCM will be working in default mode without receiving the GM high speed can bus data protocol messages from the BOSCH ECM). I looked into this myself last year(even bought the 6 speed valve body and associated components) to only find out the software was a hurdle not easily overcome.