the voltmeter is easy to install, but the oil gauges i have no experience in. the voltmeter simply takes 3 wires w/clips, inexpensive at a hardware store and spare wiring stuff is nice to have around as 240's get older.

1- Run a wire from the + on the gauge to #13 on your fuse box. don't use any other space, i tried others but #13 is the magic one.

2- Run a wire from the T (gnd) on the gauge to a solid ground point. i used the one behind the panel next to the blower motor, it already has 1 ground going there so i knew it was a solid one.

3-Run your illumination wire into the dimmer switch circut somehow, to provide power and the dimming capability.

Hope this helps,
Chuck