i have the ford wiring schematics and i know how to wire, but i have a few questions.

im installing a fuel pressure gauge, two gas gauges, a voltemeter, coolant temp gauge and a oil pressure gauge. i have the fuel gauges down but my question is this, do i have to run new sending units on the oil and coolant gauges or can i wire them into the harness, and also on my negative battery terminal i have a butt connector built into the wire, so could i wire the voltemeter into there? thanks! oh and also where should i wire up the gauges so theyll be on the dimmer with the rest of the stuff in the cabin, i csnt figure it out. :(

It depends. If the gauges have the same calibration as the stock gauges (73-10 ohms) you can use the existing senders. If the calibration is different you need new senders.

The voltmeter is best connected through the ignition switch to a switched terminal (12V in RUN/ACC) so it doesn't kill the battery over time.

Gauge illumination can be connected to the blue-red dash illumination wire to work with the dimmer.