I added AC to my 68 Barracuda using a Classic Auto Air system. The instructions were good, the parts fit fine, the AC works great. With Classic Auto Air you re use the OE dash heater/ vent/ temp control unit, with some modifications. The advantage of a new unit is the modern AC components, compressor, condenser,, are more efficient than the 50 year old parts. most likely your OE compressor needs new seals and your OE hoses and dryer needs to be replaced anyway.