What Ray and Jeff said. It is very difficult to start swapping out transmissions in a 1/2 ton deco truck and keep the torque tube. Most swaps require swapping out the rear axle, or at least the pumpkin, and welding on new axle mounts. The torque tube is mounted to the springs with a pivot mount. The torque tube prevents the axle from rolling and also helps deliver maximum amount of torque. when going to an open driveline it is always necessary to remove the old mounts and weld new spring perches on that will keep the axle from rolling.
If you decide to swap out axles or go with an open driveline, you will open up many more options for transmissions.
