If you purchase an old hang-down unit I'd suggest you get one designed for 134a coolant. However if you do want to go the old Freon 12 route, I have a brand new compressor I've listed here and you can have it really cheap. The listing aged out but I can bring it back up if you want it. Alternatively, flush the oil out of it, replace with the correct oil and 134a fittings and you'll be good to go.
I went with Old Air Products. They're all pretty similar, but Ft. Worth was closer to me.
