You might check with Kelley Blue Book and NADA to see what the truck is worth in your area. I think you can pull a report online for a small fee to see if the truck has been in a major accident. If you can find a Consumer Reports buyers guide at your local library it should have good information on the overall reliability of the vehicle you are looking at, and give you general idea of the trouble spots of any given vehicle.
At the company I work for, we run quite a few Ford trucks and they have proven to be fairly reliable with regular maintenance.