R12 to 134 conversion. What do I need??

[kalbert]

My guess is for $150 he's screwing on the adaptors, sucking it down, and charging it up.

To do it right you need to recover what's left, if any, of the 12, flush evaporator and condenser, replace o rings, orifice tube, drier (add correct amount of oil), install fittings, suck it down, charge it up, fine tune with thermometer. Probably over $1k at a shop, $3-400 at home assuming you have the right equipment for recovery, vacuum, and charge.