Cruise control, can I use Datcom signal?

[Don4107]

Our 5B has Datcom tach and speedo. No fast idle. Can I use the signal from the tach generator for cruise control signal so I don't need to run wire to the rear and have fast idle? 

Will the Rostra work with that kind of signal?  I think the King will.  Spinning the tach generator with a drill motor reads 3.5 volts AC on a Fluke DVM.  Pete?


Thanks
Don