help with DRW to SRW

[mustangman02232]

ok truck in question is a 1996 F350 XLT regular cab, 4X4, cab and chassis, 7.3 Its basically been my uncles baby since 96 (custom ordered it brand new). truck has 98k and recently had the whole front end, manifolds, turbo, rad support, oil cooler, etc done to it. the truck has never been off the overloads up until a about a year ago when my cousin upgraded to a 07 F550 after rolling his 02 supercab F350 4x4. there is also a 90 F350 4x4 that has lots of mechanical issues sitting down back in the yard that has a mint 8' SRW bed on it. So, the thought is to swap the axles from the 02 7.3 (disk brake upgrade all the way around more or less) and dropping the SRW bed off the 90 on it. I know the frame on the 96 is 34" and the 02 is 37" but can they and has anyone swapped them? or would we be better off swapping the axles out of the 90 under it? and if so is there a way to convert to disks in the back axle? any thoughts?