Replaced a top speedometer yesterday using a endoscope with a 5.5mm camera on a 77 vette with cruise control. Entering through the fire wall alongside the speedometer cable and releasing the cable from the rear of the speedometer with a stiff wire. Installed the new cable in reverse, It takes a little fanising but it`s doable. I think this was easier than pulling the dash pad.

 

Nice work! I recently did the tach cable on my '73. The little scope would have been nice...

 

It was worth a try I thought. I bought the endoscope off amazon last year for $50 or $60. worked well. I think I was replacing the original cable it`s larger than new ones. I noticed that someone before me put the cable in the housing backwards, i`m thinking it would make it easier to lube from the transducer end. When cables are in backwards that ring crimped on the cable is not pushing against the speedo head and it walks back and forth in the housing, and makes your speedometer needle bounce at low speeds 0 to 30 mph. And it was. Now I know. I placed a 90 degree 1 to 1 gear box on the transducer from the speedometer so the cable is not making a 360 degree circle, The 270 degree angle should help cable binding, I hope. I need to test it.