I've been searching the forums/web looking for concrete details on swapping out my crash box trans in my bone stock 41 GMC 3/4 ton for a newer synchronized gearbox. Probably an SM420, but I'm looking for whatever is the most straight forward swap. I can't seem to find any definitive answers on the following:

Will an SM420 bolt to my existing GMC bellhousing w/o modification? What part number should I look for?

Do I need to change out the clutch?

Do I need to modify the cab floor?

Do I need to move any crossmembers?

Do I need to change/shorten the driveshaft?

Do I need to change the ring and pinion? (no idea what ratio I currently have)


I don't care about highway speeds (it tops out at 45mph and that's PLENTY fast), I just want to increase drivability around town. Has anyone done this exact swap? Is it the same as a chev 216/235 to SM420 swap except no torque tube? I'm not finding the answers I need. Hoping someone can help me out with clear details and links to information.

Thanks!

1941 GMC 3/4 Ton