Just means I need to apply less butter to my fingers before answering questions. No, it doesn't change anything; '65 was the last year for the bayonet-type dashboard bulbs and '66 was the first year for the wedge-base bulbs. I've fixed my original answer in this post.
Might've gone to one or two.
The sockets will fit in the dash either way round. The bulbs will fit in the sockets either way round. But the bulbs will light up only with correct polarity (which is why if you install an LED bulb in a one-and-only turn signal pilot light on cars without separate left/right pilots, it'll only work in one direction). If any newly-installed LEDs don't light up for you, either reinstall the socket 180°without moving the bulb (easier), or reinstall the bulb 180° and then put the socket back the way it was before (harder).
