Not to add insult to injury but you are correct R-12 is superior to R-134a. When I worked at the dealership level and the change came, the company that had the patent on R-12 (DuPont I believe) was loosing it due to age and then sold R-134a as a “environmental saver”because R-12 was bad for the environment. Now 20years later R-134a is bad for the environment and a new Freon R-12(a) I think it’s called is now what is trying to be pushed. It’s all a money grab. There are companies that buy up surplus Freon and wait on it till the market is low and then resell at high cost. Try buying R-12 now. It’s outrageous the cost per oz. As the consumer we get hose’d for sure. Looking forward to ac in my 66 early a (Barracuda) next year but hoping the ac unit can handle the heat load of that rear window in summer. Time will tell.