Jim,
Let me know if it is available. I'd like to get it.
Ed,
Will try tying right and center together. For a while I had switched right and center but DW is starting to complain about erratic loss of sound so need to fix it.
The fan has been an "adventure". Driver's side gave me good volume but not passenger side. Both had same voltage at input. Switched fans, no joy. then decided it must be a blocked duct or air leak. Pulled ducting, everything looked good. Diverter box worked correctly. Went back to voltage. Both fans getting about 10.5 V on high. But driver's air duct much shorter with vents closer to fan, probably giving the better flow. Spoke with Gerald and he suggested adding relay to supply battery voltage to fan when in High position, bypassing resistor and using High signal wire from switch to drive relay. Fan runs significantly faster with battery voltage applied. Will finish wiring tomorrow.
Steve