The difference between the 2wd and 4wd third gen(84-88) trucks are bigger wider front fenders, different bumper end caps, and the bed wheel wells are also wider/more square on the 4x4's, everything else is the same. You can use the 2wd fenders and beds on 4x's if you cut the fenders and run a set of bushwacker fender flares.

More than tread lightly. Leave it like you were never there, nor anyone else.
'90 X-cab 4.88's 33 BFG AT's, rr ARB, Headers, Ignition upgrade, cold air induction.
'91 X-cab 5.29's 315's BFG MT's, rr ARB, custom bumper and flatbed