After much research I could not find an upgraded evaporator, so I just refurbished the stock Frigi-King, and had o-ring fittings soldered on. New R-134 expansion valve, original blower (new brushes, and lubrication), baffled the evaporator box plenum to distribute the airflow evenly out of all the vents, + 2 cans r-134a, and wow, cools beautifully on summer days in Texas!! The key to an R-134a mod is the
parallel flow condenser, the rotary compressor is also desireable (less vibration, less hp requirement, plus higher cu/in rate of freon flow, at lower rpms.)
Happy Pagoding!!!!!!