Update:
Units from parts car:
TEMPERATURREGLER #1 147 328 025
GEBLASEREGLER #1 147 328 026

First item is obvious, second device, fan speed ?, correct, or am I once again off base ?
I had thought the small box on the right inner fender was the fan speed (at least, that is how it was done on a very early Triumph I used to have, as the coiled wire resistors get as hot as a heating element, so I assumed it was a european thing).
Input requested, thanx.

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1984 300 D runs, interior
1984 300 D light hit in front, RUST, mint/perfect dash, decent interior (see above), parts car
(hate to kill one)
1998 Dodge diesel