[Fulltiming]

They are all attached/removed from the inside of the dash. The older gauges had a U shaped bracket held onto the gauge by a couple of thumb screws. Some of the newer gauges use a threaded housing which screws onto the gauge from the rear. Open up the dash, note where the wires go (it is easy to forget). Remove the rear housing or screws and bracket, and slide the gauge out the face of the dash. Place the new gauge in from the dash face side, slide the wires through the hole in the rear of the housing, attach the wires to the correct locations, thread the housing down tight, reattach the dash. Easy to say but space is limited and the number of wires inside the dash can be overwhelming if you haven't looked inside before. Most oil pressure gauges have 4 wires, a power lead, a signal lead, a ground and a wire from the light switch to illuminate the gauge when the coach parking/headlights are turning on.