Thanks for your response.
How about the digital readings on the unit? Is there anything that's just calibrated for R12? I imagine in addition to what you stated I'll also need different fittings and related components. I'd like to do work on my a/c system myself without having to go to a shop every time I open it up. Just paying for a shop's labor and $65 per pound freon a couple of times I can purchase the machine, get my 609 and do it myself.