[84 400]

The short answer is yes you can But....

2wd cabs have low hump center floor sections and 4x4 have high hump center floor sections to clear the transfer case. There are various ways to work with this but do some searching on here. Body swaps have been happening long before the internet.

You obviously will need to move over your fuel filter assembly and you will need to transfer your hydro boost brake pedal and mount. I would also keep the diesel in cab wiring harness. It's pretty straight forward swap just do your research on the floor hump so you can address that. I would do a boly in floor hump conversion but having an np208 this may not be what you want.