Just talking through all that's involved, so that you don't end up with a money pit project.
They're good axles, but pretty alien to a square body. The bolt pattern is different, the suspension is different, the differential is on the opposite side, and the steering is either stock (bad on lifted stuff) or special. For most, that more than offsets the cost of a GM axle. I doubt it's a cheaper option, but different for sure.
It would be interesting to see a coil sprung Super Duty axle under a square body, so make sure to post up if you do it!