Color me guilty of using "Freon" to describe good ol R12, but I meant it in the colloquial sense as opposed to any of the replacement elixirs........most none of which (as you pointed out) are direct drop in replacements and will more often than not result in reduced performance. Unless of course you elect to use Propane (and you know what I'm yakking about!)

Seeing as how you're much more familiar with this than I, am going to install a 1990 Chevy engine with that small radial compressor into a late 50's car and wish to use the original factory installed underdash evaporator, do you feel this is compatible? Of course I'll have custom hoses made up with the proper fittings on either end. AFAIK this compressor was originally an R12 flavor.....should I consider changing to say a Sanden and using R134 instead? Thanks

Anthony