1985 Dodge Ramcharger 409A vs R12

With all the freons out there there are certain disadvantages to certain types of freon. Your bst bet is just convert it to R-134a. There are kits with the instructions on how much to add and most of the components to change it over. They are available for around $30-50. It also makes it easier when you have aleak or take it in fo repair as it has already been converted.