Truck campers of that era , used a rectangular 6 wire connector . I'll see if I can locate a picture and diagram.
For the 120 volt wiring , find the RV's internal circuit breaker box and see what size the main C/B is 15 / 20 or 30 amp , that will determine the cord you'll need for your repair.
info on this site may help
EDIT : They show the connector in the 6 way section but no wiring diagram