I picked up a used GV unit from the salvage yard where I used to live. It was behind a 460 in an RV. I exchanged the adaptor and had them check out the od unit before I used it. Turned out the old one was on its last legs. By the time all was exchanged, they do the od units on an exchange too so you can get a fresh one, got other pieces to go with it[ minus electronics] I was within a couple hundred bucks of buying new outright. Something to think about since you are a pretty fair swim from getting parts easy.