U joint size, (297s are stronger)
High pinion, (stronger and more clearance)
Central axle disconnect, (pros and cons)
Gear ratio, (must match rear)
Mileage, (nuf said)
Are all things that might make for a bad swap.
I think I would figure out what is up w/ your axle. If you have a good axle to start with and its just in need of some U joints, go get some. If your axle is in need of a lot of work and the doner axle is an upgrade in strength w/ the correct ratio, and low mileage, than swap away.
Ted