I installed the new to me duovalve tonight. Seems to work just fine. Temps on both sides were about 77-78C according to the sensors.
Will keep updated.

__________________
All it takes for evil to prevail is for good men to stand by and do nothing.

Too many people tip toe through life, never attempting or doing anything great, hoping to make it safely to death... Bob Proctor

'95 S320 LWB
'87 300SDL
'04 E500 wagon 4matic