Classic Auto Air Vs Vintage Air 1975 plymouth Duster

Hello, everyone! Happy easter!


I have been considering putting in an aftermarket a/c system in my 1975 plymouth duster with a 225 slant 6. Classic Auto Air has a plug and play kit for cars up to 1972, and vintage air doesn't have anything for it. Does anyone have experience with installing those a/c kits? Did anything really change on the a body from 72-75?
Any and all information would be greatly appreciated!

Thank you in advance.