Does anyone have extra gauges they have put in. On my old truck I put in a vacuum gauge and i wanted to put that in my X. I am just wondering what other gauges i should put in, if any?

02 Duramax Banks everything
02 Xterra with shackles and XM radio

Just what useful information does a vacuum gauge tell you?

The only useful gauges I can think of are oil pressure, oil temp, transmission temp (automatic), and maybe voltage.

The vacuum gauge helps me drive with the highest vacuum pressure, aka the highest fuel efficiency. It also helps out as a diagnostic tool. http://autorepair.about.com/cs/troubleshooting/a/aa112401a.htm