I have a 1977 and while looking in the engine compartment below the brake booster I found a cable hanging and unattached.  It looks like a speedo cable but my speedo works fine.  I did notice that I am unable to reset my tripometer inside the car.  Could this hanging cable be for my trip and where does it attach?  Quickly on a different note, I was checking out the wiring diagrams at Doc Rebuilds website.  Have many of you found those to be very helpful?  I'm sure as you all know, I also have been battling those nasty electrical demons and need help!  Thanks to all for you help, I appreciate it!

The mileage trip meter cable goes directly from the little knob at the bottom of the dash to the speed-o head. The cable you see under the hood is most likely a leftover cable from the cruise control. Probably someone disconnected it due to a problem, or just didn't want it anymore, but left the cable there.
The cruise control equipped cars had two speed-o cables. One from the trans up to the transducer, mounted on the driver side fenderwell, and then the other went from the transducer to the speed-o head, inside.


I haven't seen one of the diagrams in person, but I hear they're pretty good.

Thank you very much, I greatly appreciate you clarifying this for me!