sounds like the typical "stuck" starter. get out the hammer and bang on the starter while someone trys n starts the truck. If you hear a click but the starter wont turn over this is prolly ur problem. the brushes can form dead spots and if they stop in this one spot they wont have a connection. hammer moves em a slight amount to get a connection. Iv had this happen to me a few times. U can replace the brushes or just give the starter several hard hits with the hammer. not hard enough to break or bend it but not light.

if that doesnt work then run a wire from ur batt (pos) directly to ur starter with key in ON position the truck should start. this will tell u if its an electrical problem or a starter problem. if the truck starts its electical to ur starter otherwise its the starter.