Not to be a downer or anything but I have a 74 Swinger and put a factory a/c setup on it from another 74 swinger it was alot of work and doesn't look the best really think hard if you want to go that route and you might even want to pull either the engine or the dash so you can make the cuts easier and make it look better or change the firewall but thats an even bigger job but as far as working you have to cut all the holes in the firewall anyway so it doesn't matter what year it is from as long as its the same engine for where the hoses conect to the condensor and a/c compressor brackets for a 74 technically they evap hoses going into the firewall should be horizontal on a 72 I believe they are vertical