I found a lot easier way to wire gauges. I have the S7 AC autotechnic gauges. If you just run the wires through the dash down into the cig lighter there is a clip that disconnects, not the big one but the single clip, take it out, put the wire in the clip and clip it back. Now there is a ground source right there on the lighter so i hooked it to that and I put it all back and that's it,then i placed the switch/dimmer under my dash. It's a lot easier to do this then to run them through the firewall and to hook them to the parking light. I didn't even have wire extensions and completed these with ease, trust me this is soooooo much easier.
Sorry I have no pictures.