1989 Ford F-150 bolt seized and broke

You can try penetrating oil but I usually have to use an acetylene torch.

It needs to have a very small but very hot tip so you can get the immediate area red quickly without heating a large area. Heat the head in a circle around the outside if the bolt without heating the bolt.

All this is assuming you have enough bolt left to grab with vise grips or something. If not, you're probably going to have to drill.
If the bolt broke on it's own from vibration and not seizure. it may spin right out with a pick.