The geartrain in the 46/47/48 are completely interchangeable from 1994 and after when we went to a 30 degree front carrier to intermediate shaft spline. The problem is if you use any 48RE parts - the drive shell, frt. carrier annulus and some other parts are unique to 48. You don;t need those parts in a gas engine. Stay with the 46/47 parts - 47 got the steel front carrier with 5 pinions - over kill for most gas engines. The rest of the geartrain in the 46 is fine for what you are doing and so is the OD unit. The 46 frt drum is likely a 3 disc, could be 4 depending on application. Just swap out the front drum (clutch retainer) to a 4 disc and you are fine. Use the L/R drum retained with a snap ring and have the ORC race pressed on the L/R drum - this greatly reduces the ORC failures experienced by prior model year units without these improvements. Do not use a L/R drum without the race pressed on.

All 48RE had 5 disc front drums in production from 2003.5 - 2007, both in the diesel and SRT gas trucks. We never offered a 6 disc drum in production.