For what it's worth, I had a p.p.i. done on this car about a year ago but a reliable shop in Denver; it wasn't clear what the under-dash switch was, although the fog light was original to the car. I'm tempted to make inquiries to the eBay seller to see what's been done since I had it looked over, but it'd just be idle curiosity at this point for me. If anyone has any serious interest in the car, I'm happy to share what I learned back then. I guess it's obvious that I bought a different car. But this one was my favorite color combo.
Rick
Dallas TX
1967 250SL, 4-speed