Another think to watch out for on the axle swap is, at least on the half tons with which I am more familiar.
The 72 W200 should have a divorced 205 transfer case with lockout hubs and the 75 trailduster should have a married fulltime 203 transfer case with solid front hubs and an issue you will most likely run into is the 72 W200 front axle has a different pinion angle to mate up with its divorced transfercase so you will end up with a funky pinion angle and possibly some drive shaft issues if you put the the W200 axle with the 203 fulltime transfer case in the trailduster.
The 75 Trailduster has been fully converted to a 1993 Ramcharger 360 MPI engine with a 518 4 speed automatic and the non full time transfer case.
I want to swap over my 72 axles as they are part time drive and the transfer case now supports this. I can't install my front driveshaft until I do this.
I agree on the pinion angle. Better to swap the 8 lug w200 knuckles/hubs/stub shafts on the full-time axle.
The 72 W200 has 8x6.5 bolt pattern. Very common pattern. Stock gm wheels will not clear the rear axle hub. Factory ford wheels will clear the hub.(ford changed the 8 lug pattern in the late 90s and the newer ones won't work.)
Could also swap to 5x5.5 bolt pattern with 80-93 ramcharger/w150 knuckles/hubs/stub shafts.(Probably the best option if you want locking hubs unless running tires bigger then 35s.
Mile-marker made a hub kit for the 5x4.5 bolt pattern but it keeps the weak design of the 75-79 full-time dana 44 bearings.
Or balance the front shaft and put it on with the full-time front axle.
