Goach2. The housing on the end of the trans can be swapped. The open trans will fit just fine, in place of the "closed" trans. You will need to take all the bits from the torque tube trans and put them on the open one if that is the way you choose to go. The speedometer drive is a matched pair. So that will have to be changed over as well. 4.10 is standard for the 1/2 ton. So that set should work just fine. The housing on the tail will match right up, so will the trunnion bearing support. Gaskets sets often come with both sets in one box. There are some differences inside the 48 vs the 56. Some loose bearings vs a caged set. But the gaskets are all the same. I even think the speedo drive will swap just fine. The 48 is a good one, so just re-gasket, swap the speedo drive and you should be fine. No major disassembly would be needed. Read the manual to set the "ball" seal shims and put it back in. Washing will be the worst part of the job.

Steve H