yo Ron,
re: "96 uses a different key for the tailgate than for the doors. The door key is also the ignition key..."
That is Normal and same for my 96 that we bought new
Also;
Door Lock Replacement, & ignition, storage, etc. TSB 99-24-2 for 96 Source: by Ford via Chilton
From my 96 Bronco Workshop Manual
Lock Cylinder, Door
NOTE: When a door lock cylinder (21985) is replaced, both door lock cylinders should be replaced in a set. This will eliminate carrying an extra key which will fit only one lock. If a key is to be replaced, the new key code number is stamped on a metal tag attached to the key.
Removal
Roll the window up.
Remove access hole cover and/or front door trim panel (23942) and pull away watershield, if equipped. Refer to Section 01-05.
Disconnect the front door latch actuating rod (22152) from the lock door latch operating lever.
Slide the lock cylinder retainer away from the door lock cylinder.
Remove the door lock cylinder.
Installation
Follow removal procedures in reverse order.
Lock Cylinder, Tailgate, Bronco
Removal
Remove interior access cover panel.
NOTE: If glass cannot be raised, remove glass. Refer to Section 01-11.
Raise glass.
Remove lock cylinder retainer.
Disengage lock cylinder from switch.
Remove lock cylinder from tailgate.
Installation
Follow removal procedures in reverse order.
Glass Replacement & Parts Break-Out Diagram in a 96 from 1996 F-150, F-250, F-350, F-Super Duty and Bronco Workshop Manual; "...Open tailgate. Remove inside cover access panel and retaining screws. Remove inside cover panel support and retaining screws. Remove inside cover watershield. Manually close both tailgate latches and raise the tailgate glass. Remove four nuts retaining tailgate back window glass (42006) and back window glass bracket (422B18) to back window regulator. If tailgate has heated glass option, disconnect two terminals (driver's side). Grind off four rivets, two on each back window glass bracket to tailgate glass. Punch out four rivets and remove four door window glass channel bracket retainers (234A46) and door window glass bracket spacers (234A44). Remove screws and pull out tailgate upper corner seal assemblies, one on each side. Snap out inside and outside tailgate weatherstrips with tool. Slide tailgate back window glass out from tailgate assembly. Installation, Slide glass midway into tailgate assembly. Connect heated glass wires, if equipped. Install back window glass bracket C-channels onto the tailgate window regulator arm slide guides. Position tailgate back window glass over back window glass bracket C-channel studs and install four door window glass bracket spacers, door window glass channel bracket retainers and rivets. Lower tailgate back window glass to connect heated glass wiring terminals. Close tailgate and cycle tailgate back window glass to ensure smooth operation. Install watershield. Install inside cover panel support (one *****). Install ten inside cover access panel screws. Close door and cycle tailgate back window glass to ensure proper function..."