Measure your battery compartment. Two six volt Trojan T-105 batteries may not fit the battery compartment. Test the converter charger, it may not be working. It would be a good idea to replace an old outmoded converter charger with a modern one that will not boil out batteries when left on shore power.Recommend a Progressive Dynamics PD-9245 or equivalent If you use two six volt batteries in series for 12 volts, you will need a short interconnect cable. Replace the negative cable that goes to the frame with a black one. Suspect other amateur wiring fixes, etc. common on older rigs.
Make sure that tires are less than 5 years old by date codes on tires for your safety. Have brakes inspected and repaired as needed for safety. Have cooling system checked including, radiator, water pump, clutch fan, and all belts and hoses.