You're right, the Forum is titled 80-96. That's because the BASIC body/tub never changed in that time, however there *were * significany changes and upgrades worth noting. The 80'-96' trucks break down into three distinct subgroups:
1) 80-86: These trucks are notable because they're slightly smaller than the 78/79's but the *primary* difference is the loss of the solid front axle and the addition of the IFS (twin traction beam) front end.
2) 87-91: Thesew trucks saw the introdution of Ford's first *aerodynamic* front end as well as the crossover from 3-speed to 4-speed Overdrive transmissions.
3) 92-96: These are the final and definative word on late model Bronco's. The front-end Aero package was revamped to gain more hp & some style points but that's about it.
F-trucks are always a good parts source but I'd stick to 87-91 parts just to be sure. Unfortunately Ford parts can be a stone cold bitch.