1966 cj5 guage wiring question

[66jeep]

I'm putting my cj back together now, and although I have labeled everything fairly well, I did not label three wires that come off of my tach guage, oil pressure guage, and water temp guage..... all three of these wires pig tail together into one connection. oil pressure and water temp have mechanical sending units, tach has some other wires that I know have been replaced properly. the wires in question have a bulb for the tach attached to one, the other two were simply attached to the top center post on the back of oil and water guages. I think the unlabeled connection should be power for the tach light, and oil, and water guages, and should connect to the main speedometer cluster so all guages light up and work upon ignition??? I just am not certain. any help on how these guages get power and ground would be much appreciated. I'm unable to post pics at this time but will get some up if I can't figure this out before to soon.

 

[Torxhead]

Where they pigtail together should be switched power, or power on when ignition is in the on position. Your gauges might have a connection to the light switch, the sensor for the tach is the negative terminal at the coil. Then the gauges need a ground if there is power going into them. I'm thinking these are aftermarket gauges and you should be able to check with the manufacturer or website for more accurate info.