Ok, there are 2 types of Rallye gauge clusters; one has a cable that goes from the back to the front and connects to a knob in the fascia that allows you to set the clock (I believe the odometer has a similar arrangement). This was a 70 and perhaps early 71 feature if I am not mistaken. 72-74 used a knob that goes through the lens and connects to the odometer and clock.
Sounds like you are talking about the cable to set the clock, is there a hole in your fascia (wood-grain area)?