a couple years back in a Mustang gathering, saw a 65 that had an original lp player under the dash! I think it played 7" lps, but can't imagine what would happen going over bumps and all...
Back in the day I know Chevrolet offered an underdash record player as a factory option.
The idea was NOT to try and play while driving but for when you were parked say watching the sun set or by the beach or boardwalk.
But I am sure some tried while driving, I can only imagine the results!
I did see one in a 55 Chevy at a local car cruise meet, no idea if it worked though as never saw the owner around the car or would have asked.