When I was younger(back in the 80's), I had three street cars: a 70 340 dart, 69 superbee and 65 426 coronet 500. I had wired each one with a harness like the one below and taped the plug under the dash near the steering columns in all three cars. and wired the tach with the matching end so I could swap the tach from car to car at any time.
