1972 Ford F250 camper special

1972 ford f250 camper special with a 360 & 4 speed transmission(has trouble going into 3rd gear sometimes sycros?). Truck almost all original. runs and drives well . Head Lights . blinkers. emergency light. horn. etc. All work the only thing currently not working is the stereo ( might be a fuse ?)Just put in a brand new battery along with a tune up . ruck also comes with a rebuilt 351 FE big block motor . The guy I bought the truck from ( second owner)bought this engine just is case anything were to happen to the engine that's currently in it.