there's no way to know
I'd be surprised if the original Freon (R-12) was in it. How long have you had the car? Have you ever had it recharged?
It might be simpler to indicate HC-134a is in the system. You can recharge with it, nowadays no one still believes the hoses and seals have to be changed out. R-12 is _very_ expensive... HC-134a isn't as expensive, but it isn't cheap either.