God I love them, they're so sexy. They all seem to work, I'm not sure about the speedometer though, it seemed to be acting funky. We made another panel using the old one as a template, cause there was no room for all the gauges, these ones were bigger than the VDOs I had in there. Yes, the tach is different. We put this together using gauges we already had, I plan to replace the tach and the fuel level at some point soon.
I don't know what gauge it was.. but you'd want to use something around 1/8" thickness. We used something that was really thin, but we had the previous gauge setup as a backing plate.