I had the original /6 cable fray and stick on my car accelerating onto RT 22 in NJ - very exciting. Tap agiain and rpm went up. foot on the brake move over 3 lanes and turn the key to off.
Anyway. Yes you need to know the way the cable clips into the firewall. IIRC '67 is a U clip or E-clip and the later ones are a plastic prong into a square hole. That's my story, but I won't stick to it if its wrong.