This is not a difficult swap. I'm guessing you're planning on using an SM 465? There are a few things you will have to change. If you're getting it out of a doner, make sure you get all the clutch assembly, linkages, boots, and pedal assembly. If you want reverse lights, make sure to take the wiring harness from the transmission switch to the cab. The wire connector is nearly impossible to find and the automatic wiring goes to a switch on the column. The only other thing I can think of is the rear drive shaft will need to be lengthened. Changing from a TH 350 to an SM 465 was the best move I ever made on my truck!