I guess it depends on what you are wanting to swap. The IDI's came in 3 different generations of truck. They were:
83-86 - Slantnose or Bullnose. That body style went 80-86, but there were some cosmetic changes in 83, along with offering the 6.9L Diesel for the first time.
87-91 - Bricknose. Trucks were basically the same the entire run, with the exception of the 6.9L still offered in early 87, the changeover to the ZF-5 for the manual, E4OD for the automatic, but a C-6 was still and option, and the change to the 7.3L in late 87 early 88.
92-94 - OBS - Old Body Style or Original Body Style. This really started in 94.5 when the 7.3PSD was introduced and it was the old body style truck with the new engine, or the original body style with the PSD. This body ran from 92-97, but only 92 - Early 94 offered the IDI, and only the late 93/early 94 had the Factory Turbo option, along with an N/A option.
Some things are more closely related between generations vs others. But, there is subtle differences in EVERYTHING between the 3, nothing is exactly the same between the generations.
For Example:
Core supports are gas/diesel specific, and generation specific. A Slantnose core support will not directly swap out with an OBS.
Everything sheetmetal and cosmetic in front of the firewall. Fenders, hood, cowl, grill, lights, running lights, bumpers, badges, etc are all different.
The cabs are the same size and same basic shape, but the dash mounts are different between the 3 gens, the firewalls are different, and on the extended cabs, the Slant and Brick have the divided extended cab window, the OBS is 1 piece.
Doors are the same size and basic shape, but the interior panels are different, the vent windows are different sized and interfere with the dash. You can, for example use a slant door in an OBS, but when you open the vent wing, it will hit the dash.
Obviously the dash assembly and instrumentation and controls are different between the 3. The way the dash mounts in the cab is physically different, the steering wheel is different between the 3 generations, and the slant/brick column will not fit in an OBS and vise versa. Pedals and pedal boxes are generation specific, as well as the clocking on the clutch master, if so equipped. You can swap them around and they will work, but the master will not sit in the correct position.
The slant bed and tailgate is completely different with different rocker panel lines, and the "chamfer" at the top of the bed is different, as are the shape of the tail lights vs the brick and obs bed. The brick and OBS beds and taillights are the same, with the exception of the 97, there is an additional "crease" along the rocker that is not on any other year.
The windshields are physically the same, but the location of the VIN plate in the dash is in a different place in the different generations. So, if you put a brick windshield in a slant, the black border on the windshield will cover the VIN because the notch in the black to accommodate this, in a different place.
On the crew cabs, the rear door are the same size and shape, but the slant has a divided window, with a small, stationary window about 1/4 the size of the opening in the front, and the rear 3/4 portion opens. In the Brick and OBS, it is 1 solid, window that opens. Before the mid 90's OBS's, and we are not 100% sure when the changeover took place, but we do know it was done by 97, if the truck was equipped with factory power windows, only the front doors were power, the rear doors in the crew cab still had a crank. 4 power windows were eventually introduced, but much less common that 2 power, 2 crank.
Now, engine parts and entire engines will swap back and forth, but 83-~91 the engine is a V-Belt accessory drive, the 92-94 is serpentine, but all the brackets and pulleys can be swapped to maintain the original setup, if you so choose.
Some interior parts will, like seats, I believe floor coverings, and things like this. The interior door panels can be swapped, but they will not match the lines of the rest of the interior.
The Slantnose trucks have a metal, chromed interior handle, the Brick and OBS have a black plastic handle. These like to break off, but the slant handle is the same size and shape and can be swapped in. I have seen this "upgrade" many times.
Most other power train stuff will swap, but there are difference there also. The early slants have a Dana rear axle, late slants, bricks and OBS's have a Sterling 10.25. But there is an early short pinion Sterling, and a late long pinion Sterling, which means the rear driveshaft is a different length.
I guess a more general answer is, you can swap most anything between generations, but, it won't necessarily be a direct, easy unbolt one, and bolt the new one on. Even the "simple" upgrade of swapping an OBS doghouse onto a Brick or Slant, is not as simple as it sounds.... and not all the body lines at the cowl will match, due to the subtle differences in generation.
I know this is a long post, but if there is something specific you are wanting to transplant, it may be easier to ask if that particular item can be swapped, or what work need to be done to be able to swap it.
) to remember when the 80 Slantnose first hit the local Ford Lot. I learned to drive in our 83 F-150 (one of the reasons this is my favorite body style). I also remember the first 87 Brick I saw...... we were amazed at "How Different" they were than the Slantnose...... and those HUGE headlights and flat tailgate, it was like nothing we had ever seen. 
