Welcome to the board.

First the truck does not have full time 4wd unless the previous owner swapped in another drivetrain.

Second, If it does not have manual hubs and the owner has been driving it around in 4wd on the street claiming it has "full time 4wd" just run away now. You now know why the trransfer case is messed up. <img src="/forums/images/graemlins/lol.gif" alt="" />

It sounds like a great parts truck or budget wheeler depending on what else is messed up. If you know how to turn a wrench and want a project pick it up. Otherwise run the other way fast.