I have ... however it's not a volt gauge but a I/C temp gauge. I was thinking about installing a volgt gauge next to it but then again i figure these are kind of useless in my setup and ran out of room anyways.
Nvm the white foam ... temporary stuff to hold the gauge in place.
I'm still looking af an OEM "aux" in port that replaces the ashtray so i have a flat face to make the cutout in for the gauge. Like this:
Unfortunatly these are hard to come by ... especially in europe.