It comes out below the steering column. I have two at my place up north Id measure them but I am working out of town till the 22nd
Are they 4 speed cars that had the passenger side speedometer gear in the tailhousing? I don't know about 65 but by 67 the speedometer cable exited the firewall in a different spot and was unique on Muncie equipped Beaumonts/Chevelles.
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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