Cheers guys, I can't find a website for Autogauge at all. The only data I can find is for their range of manual boost gauges.
As you can see on the second picture, there are two loom connections going into the back of the gauge. One of them runs to the sender itself, and the other has got yellow/black/red wires coming out. I'm assuming these are for 12v/ignition live/earth.
Alex: If you could scan it in then it would be really helpful, cheers.