HA! I realize only now that my text to the pictures has not been sent at all. So of course it all makes no sense.
Many thanks for the hint.
So again:
The part number indicates an RHD loom. Excitingly, this number can also only be found in a Japanese book. My documents of the US and EU models do not have this number.
This is also very much in line with a forum post I found on the subject: https://zclub.net/community/index.php?threads/what-relay-plugs-in-here.26694/page-3
"24013-N3305 - ASSY - HARNESS INSTRUMENT 07-72 thru 07-73 (HS30). Looks like a stock RHD Export instrument panel harness.
24024-E8200 is a little more obscure. I don't see it in either the R-Drive Export or L-Drive Export factory parts lists, and the 'E82' prefix indicates something first used/developed for the Japanese domestic RHD S30 models for 1971-on production. More specifically, it is in the Japanese market factory parts list as HARNESS - ACCELERATOR - HEAT GLASS & COOLER (superseding 24024-E4100 and 24024-E4101) and - looking at what section it is listed in - it may originally have been designed for the 'Standard' (no frills) model in Japan from '71 up, allowing a factory aircon ('cooler') unit to be installed as an extra cost option. It may then have been fitted to some RHD Export cars in connection with the heated rear window, with the extra connector for the cooler sitting like 'tits on a bull' or an 'appendix/nascent monkey tail' (take yer pick). I can see this on the Japanese market wiring schematics."
Maybe that's why the switch doesn't really belong in a US car?!
I love things like this!