If your 1972 C10 was a factory AC truck from the beginning, putting it back is easy. If it was a Heater Only truck, there are firewall modifications that will have to be made. Adding AC is not an easy task. If you're comfortable with the mods, the factory AC system is much better than any aftermarke...

Was the condenser included in the Underhood Replacement kit? I would think so, but you seem to indicate that it wasn't. Either way, that's a bummer. Your old OEM style R12 condenser is available as a repro. A Google search should find a few vendors. However, many folks rebuild their systems for R134...