BCDD and vacuum advance question

Just lately,I had an issue with my 77 280 running excessivly rich.I figured out it was a bad fuel pressure regulator,and a stuck injector.I replaced FPG,and all the injectors,and now she runs well.While I was replacing these parts I noticed a green wire that was cut.It goes to what looks like some sort of sensor that is threaded into the side of the BCDD.I also started car and pulled vacuum hose going to vacuum advance unit from BCDD unit.Even when I revved engine to 4500 RPM,and then let off throttle suddenly,there was no sign of any kind of vacuum.Is there suppossed to be?Also I remember faintly something about VAC. ADV.not kicking in until 5th gear was engaged.Sound familiar to anyone?{Anyone know where the green wire might connect to?}