Not sure on that. As an auto parts salesman I can tell you this. You can usually pick up a remanufactured unit for $100-$150 with a lifetime warranty. Buying one used is just asking for trouble especially if it has been sitting around somewhere for an extended period of time. This booster is not specific to the '84 Turbo Regals. They can also be found on 80's diesel G-body's. If you do get a remanufactured unit, ask the salesman who manufactures them. Some may be too ignorant to know or find out. You want to look for a Cardone unit. I know both NAPA and Carquest sell them. They just put a NAPA sticker over the Cardone sticker.