Some cars are just "converted" by changing the high and low charging ports to the 134 type, vacuuming the system, and recharging. A "proper" conversion will include at the very least, changing the expansion valve which is located in the passenger side footwell. When you remove it, be careful not to kink or break the thin metal line that runs to the a/c temp switch. Take the switch too. You might also want to grab the delay relay located very close to the control switch in the console. Some conversions included changing the evaporator to a larger one. The evaporator is in front of the heater box and can be removed from the passenger footwell. If you are really lucky there will be an electric condenser cooling fan behind the grille, grab that, the condenser and the hoses. If your system has leaked all of it's refrigerant, it may have come from one of these sources. Since you are taking all of this, grab the compressor, too. Good luck!