R-134 should be the refrigerant as R12 was banned in 1996.
Freon is R12. Your 1997 Chevy uses R134 Refrigerant.
r-134a
r134
R134a
r134a
R134a
R134a
In a 1997 Ford Aerostar : Refrigerant 134a is used
R134
It takes r134a refrigerant.
134a refrigerant
R-134a