I changed the rear end in my 36 5 window for one from a 40 pick up. The torque tubes were different lengths, I don't remember which one was longer, so I just switched parts between the two. I t also required changing the drive shaft and if you have to do that be sure that you get the pins seated in the collar or they will work loose and over time will destroy the u-joint. The 40 rear end had more leafs in the spring than the 36 so I took the center pin out and removed leafs till I got the right pack. Be careful with the brake lines as they tend to bend very easily.