Let me see if I have this straight...

2WD TH350's will have a longer output shaft for the driveshaft slip yoke, and 4WD TH350's have shorter to input to cases?

Question is this. Is it as simple as swapping/cutting output shafts to turn a 2WD into a 4WD?

it is that simple, but the trans must be completely taken apart to do this.

Also, you'll need the factory adapter that goes between the trans and tcase, where the current extension housing is.

A guy wants my SM465. I want a TH350 for my mud truck. He has one, but it's for a 2WD needs to be rebuilt (maybe). I was going to have him have it set up how I want it in trade for my 465. Therfore it wouldn't be a big deal when they're re-building it to throw on a different output shaft on it huh? Thanks!