easy to do, just alot of nuts/bolts to do it. If you have access to "heavy lift" (forklift/overhead lift) you can try and unbolt the extensions with winch/bumper installed, and put the whole assembly on the other truck after you remove it's bumper. One good weekend worth of work at the most with the right tools. or perhaps a long days worth if you find a buddy to assist.
Prep is key. Coat all the nuts/bolts with your favorite rust buster (WD-40/PB Blaster/etc) and let it soak in for a few days to facilitate wrenching.
You will need new 3 PTO gaskets. one for the tranny/PTO seal, one for the PTO's inspection plate so you can check for "click click" (backlash) on the PTO gears so the PTO doesnt destroy the tranny, and one for the inspection plate for the donor truck.
Also, check the PTO shaft seals for leaks. When it is out of the truck is the perfect time to replace them if needed.
Dont forget the 80/90 oil to put into the tranny's.
Not a hard job, just a bit of PITA because just about every bolt you need to work on is 3/4 inch. Air tools will help alot.