OK now the rest of the info comes out. 73 the A/C completely changed, so you can use systems for 67-72 for the same and systems for 73-76 for the same, but there are too many changes to switch the two.
Be aware the plan is to pull EVERYTHING from the Dart dash forward including the engine, k-frame, evaporator, ac lines, heater box, power steering, engine, AC compressor, dash, ducting, controls, steering column. The Duster is bare sheet metal firewall forward.
