I have answered part #1 of my question - found pictures of the check valves in dmorrisons wiki article on Evaporator replacement.

http://www.peachparts.com/Wikka/W123Evaporator

__________________
-------------------------------
'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car