I am in the process of re-wiring my truck so I've got the gauge cluster out. I want to re-calibrate the tach while I have it all apart.
As a safety check my question. There are 2 wires going to the tach - one is for the tach signal from the distributor - can I safely assume that the other one is battery?

While I am in there - any reccommendations on how to test the "charge indicator" gauge? (is it a voltmeter or an ammeter?)

Thanks

Thats correct the second wire should go to ign unfused on the fuse box. The meter is an ammeter and there is a 4 amp fuse by the battery junction block and another by the drivers side of the rad support.

Thanks a lot for the info. I'll see if I can mock something up to test the ammeter before I put everything back together.
Thanks