I love these GAST vane driven vacuum pump/compressors. They are dirt cheap to find in surplus houses and on ebay. Usually scavenged from industrial equipment like printing presses and docu-copying centers, they make for excellent projects. The 220v models usually sell for just a few bucks, while the 110v models garner a premium.
My old GAST "bit the dust" after almost 20 years of service, so I picked this one up for $10 at a local surplus center and will turn it into my new AC vacuum pump. The combined R12 and R134 AC gauge fitting was picked up a few years ago at Enco for $5.00. This will allow me to hook up my older cars as well as the new 134a systems.
It's sports a GE 1/4HP 220v motor -- plenty enough for pulling a vacuum on a car. All I need is a plug -- which I'll pick up tonight.
BTW -- using these units as compressors makes them the perfect candidate as a fresh air supply when using toxic catalyzed paints. I converted a 110v pump a few years ago and it works just like a professional fresh air system.
EDIT: I put a plug on it, did some re-plumbing and hooked it to a vacuum gauge -- it held 32" of HG. Plenty for AC work
(http://i357.photobucket.com/albums/oo18/goodfellow_2004/misc/PICT0402Medium.jpg)
(http://i357.photobucket.com/albums/oo18/goodfellow_2004/misc/PICT0403Medium.jpg)
(http://i357.photobucket.com/albums/oo18/goodfellow_2004/misc/PICT0404Medium.jpg)
After re-plumbing and a new plug it looks and functions real well. I'll recharge the AC on my truck with this pump tomorrow.
(http://i357.photobucket.com/albums/oo18/goodfellow_2004/misc/PICT0406Medium.jpg)