What year is your car? Most companies switched by 93, I cannot think of a 94 off-hand that has R12.
And, to everyone, a conversion is MUCH MORE than just a fitting swap, despite what AutoZone wants you to think. Proper conversion is complete drain/flush of the system (which requires removing the lines, flushing equipment, etc), refill of the proper oil (R12 and 134 use different oil), evacuation, leak check, and charge.