R134a is all that is available If you have an R12 system You have to retrofit to R134a I didn't go through the hassle of changing the entire system to r134a I just recharged the system with the new freon and it's working just fine. The coolant even last longer.
It depends on what kind of freon you need.
R-12.
R134a
R134a
R134a
R134a
R134a
R134a
It was built with R12, but will need to be retrofitted for R134a.
If you asking what type of Freon is in a 1993 Aerostar, that would be R12. If you need to get it recharged, you will need to have it converted to R134A system since R12 is no longer available.
Was built for R12, should be converted to R134a
A 1998 Chevy Camaro uses R134a.