91 was the first year for the 6 bolt wheels. 87-90 still had the 5 on 4 1/2 bolt pattern.

If the reason you are looking at the 87-90 is the 5 bolt wheels, a simple rotor swap will fix the front up to the end of the 1996 model year. Tell me your going to rebuild the brakes on your project. Just buy the 87-90 front rotors for the 91-96 chassis (wheel bearings and everything is the same). The 8 1/4 or the 7 1/4 rear ends (if you really want to keep those) can be changed from a 6 bolt to a 5 bolt by changing to the same size 5 bolt axle shafts and changing the rear drums.

The 97 and newer have a different wheel bearing setup, changing them to a 5 bolt is not cost effective.

The Dakota wiring harness is pretty simple up to 90. 91-96 Dakota harness is more simple then the same year Ram, the Dakota system still has the efi separate from the rest of the wiring unless it has the overhead consel thing. I used a 90 Dakota wiring complete in my coupe. When we did the 97 5.9 into the 57 Dodge wagon, we bought the Hot Wire harness. Gene