Don: Although there is an access hole in the rear of the body, that is for access to the CONNECTIONS to the fuel line and gauge air line. Once those are
disconnected, the tank must then be removed from the car to service the sender. Not what you wanted to hear...
REMOVE:
Spare carrier or cross bar, frame horn covers, bumper and brackets, tail lites and stands, then remove (3) bolts securing the tank to the frame. At least one bolt has a spring on it (like radiator bolts) or all 3 sometimes. Then slide tank out the rear. Now can remove the 6 screws holding the sender to the tank and one bolt holding the lines to the front edge, then lift the sender out...