Looking at the EPC I see 4 vacuum pods:

One is way high on the air box p/n 201 800 08 75 with no functional description although it appears to be near the air mixing flap control resistor.

One is right on the driver side of the air box p/n 201 800 05 75 (or 000 800 87 75 from VIN F 002651) for defroster flap control.

One looks to be deep in the driver footwell p/n 201 800 03 75 for footwell flap control.

One is somewhere on the driver side p/n 201 800 00 75 called main air flap control.

Seeing as non have the same part number I'd say they're not interchangeable.

Sixto
93 300SD