Outer Limits 4x4 Board

I have played around with the coil and alternator for the gas conversion., but now the tacho doesn't work on my 88 range rover. Where the hell is the tacho wire on the alternator or the coil, and whats it look like, or could there be another problem

Its on the alternator, and from memory its white.... Just jiggle the small wires on the back of the alternator and see what happens.

problem is it's a ford alternator, but the wires should be the same