Not that I know of besides the junkyard.

Heat works fine while stationary, defrost and footwell are toasty. When I get up above maybe 20 mph the heat is no longer coming out on my feet. Does this sound like it would be fixed by the monovalve repair also?

Does the air from the defrost vents go cold above 20 mph too? If so then that pretty well matches my symptoms as well as those of the member who started this thread, so I'd be inclined to say, yes, you have the same problem.

If the air from the defrost stays warm, but just the airflow to your feet stops, I'd be more inclined to think it is a problem with the contoller. The solder joints on the board break and then airflow direction and control goes all whonky from what I've read - but I'm certainly no expert on these systems - still learning myself.

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1984 300 Coupe TurboDiesel
Silver blue paint over navy blue interior
2nd owner & 2nd engine in an otherwise
99% original unmolested car
~210k miles on the clock

1986 Ford F250 4x4 Supercab
Charcoal & blue two tone paint over burgundy interior
Banks turbo, DRW, ZF-5 & SMF conversion
152k on the clock - actual mileage unknown