What year Danny? I've done a couple 99-04 2wd to 4x4 swaps. On my Ma's 2wd reg cab 00 F250 we found a donor reg cab F250 4x4 & swapped everything over. Took a couple days in the middle of winter without head & no air tools. :doh:
Hardest part is grinding the rivets off the 2wd coil buckets & wrestling the TTB out-
Unbolted the axle/springs/hangers as one unit on the donor truck. No grinding/cutting required-
Just slide under & bolt up with pre existing holes-
Calipers are interchangeable AFAIK but you'll need to unhook the line when you pull the coil bucket off. You'll need the trac bar bracket & the 4x4 tie rod/steering linkage. You'll also need to pull off your 2wd pitman arm & swap on a 4x4 pitman arm, I got a brand new Mooge for around $60 at O'rileys. Switch to 4x4 front shocks, swap the transmission to a 4x4 tranny or have a shop take your tranny apart & swap the tail & get a T case, drive shafts & your done.
The other 4x4 we did was on Trailerhauler's early 99 F350 dually.
Grinding the old buckets off-
Getting the 2 rivets on the bottom of the bucket-
Differences in the 2wd vrs the 4x4 pitman arm-
Buckets off-
Axle set in place with 3 people & 2 floor jacks in about 45 mins-
On an 05+ it is bolt on as well, no welding/fab work should be needed.