I think the only difference you'll find is in the way the grille is designed. The 87 had a separate grille and bezel (in fact you could easily put the grille in upside-down), whereas later models have part of the trim incorporated in the grille. If you're swapping, make sure you get all the pieces for the grille.
The fenders, liners, bumpers, lights, etc. are all the same, as are the doors and all the glass. So are the suspension control arms, track bar and steering linkages. The axles will be different, though you could likely interchange the whole thing as long as you don't mix. The 87 has different knuckles with a separate brake caliper bracket, and the disconnect axle. The hubs, calipers and rotors are different as well.
The steering gear will be interchangeable, but may have a different boost level. Early ones had more boost. The steering shafts and columns are interchangeable, as is the PS pump.