I have a 1968 Ford Bronco that has no headliner in it at all
I have a 1968 Ford Bronco that has no headliner, only bare metal; do you have a kit for that??
You have 2 options for your 68 Bronco without a headliner- 1st one is to fabricate a headliner board from 1/8 inch plywood/louan/cardboard and cover it with headliner material or; 2nd a headliner can be glued directly to the metal in the Bronco. It won't last quite as long as an automobile with a headliner board, but it will stay up there a while.
The tricky part, is to figure out how you would want to trim off the edges of the material (not too bad if you have interior trim in your Bronco), and also measuring to make sure that you get enough material. This could be a challenge, if you are up to it!