Wiring
The tach has 3 wires, it should be from left to right looking at the back (I, G, S) (I) should be coming from your ignition switch and is probably purple jumped from instrument to instrument. (G) is your ground wire. (S) is probably a gray wire. Now the alternator, Looking at the back of the Motorola alternator. You have a rectangle box just below it and to the left there should be 2 bolts with a wire on each. That top bolt should have the gray wire from (S)termenal on the alternator the second bolt has a wire running into the box on the left side. Lower end of the alternator is the wire that goes to the starter. Now we are at the 2 bolts on the right side of the box the top one is probably purple and runs up to the ignition switch. and the lower of the 2 bolts runs back into the box. The glow plug switch should have a purple wire from the ignition and the other wire should run to the first glow plug or solanoid if you up dated the wire run. I hope I made this clear enough.
