I'm pretty sure I queried this when I did my 70 4 speed conversion, and the answer was it enters the firewall in the same place as a cable for an automatic. The routing was in question though.
Mark, don't you know someone who has that answer???!!!
It goes parallel with the firewall across the back of the engine and then enters the car at a spot where there is a triangular depression punched in the firewall behind the driver's side valve cover.
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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
Yes, I was pretty tickled to see it there with overspray intact when I bought the car. I do have a spare but this one is the original with the right date code on it too.
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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
Yup, the dimple is there. I just need to get a grommet to know the size and then time to figure out how to make the hole.
My plan is to keep the old grommet in the old hole and that will function as the hole for my temp gauge and oil gauge connections when I add the gauges.
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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
'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.