Unit has original B&W SONY back-up camera...still works...sort of...want to replace with modern color camera hooked to Good Sam GPS. Anybody know if I can possibly use the existing old video cable?

I replaced my back-up camera with a color camera and monitor.
See Here I don't know about Good Sam GPS.

My original Sony had both picture and sound so when I installed a Pioneer Radio/DVD/ etc with a backup camera I used two of the existing six wires. Works great.