Victory!!! After plugging a brake switch everything is fixed. Rear lights go off, dash lights go off and dim! If anyone is looking for a brake switch in Canada - I discovered this one, it's for Jeep but looks pretty similar to Impalas, so I got it and it turned out 100% compatible with Parisienne. www.amazon.ca/dp/B0030V9ODA Yaaay.
Yes, that looks identical to the original GM switch!
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)