Thanks for the info! To add to that I have now found an SM420 for the truck. It's been 40 years since I removed a transmission with a torque tube. My question is does one need to move the tube down and remove the 4 sp from the top or vice versa? And when rotating the tube should I loosen all the u-bolts on the differential so I don't bend the tube. Any guidance will be appreciated.
I found it easier to remove the SM420 from the bottom but I also removed the floor cover to make the whole process easier. I was working by myself and strapped the trans to a platform jack. No way could I have man-handled from below like I used to do with 3 speeds a few decades ago. Have the back of the truck on jackstands so the rear end will rotate easier as 3B described.
I used guide rods the first time I replaced the trans but found it easier without them the second time. I got to do this twice because since I struggled getting everything lined up it looked Like I could get the throwout bearing arm in place after the trans was in. I couldn't.
