I've got a 47 Mack EF and I'm thinking about swapping in a 6BT to make it a useable hauler. The plan is for a flat bed to move the machine tools that follow me home and to pull my 7-ton trailer. The question is what transmission is up to the job? The truck has a MGVW of 12,000 lbs and has 5. 56 gears. Looks like I need something with an OD but what will hold up? Thanks for the advice. Bob