I also had a couple of oil pressure gauges melt on me. I used the electrical ones that look stock. The +12V hot wire will melt it if you connect it to the terminal near the plus sign on the gauge. Turns out that is for the voltmeter gauge that uses the same backing. I switched the wiring to the correct way on a new gauge and mine has been fine.
1978 CJ5 - 304 V8 - Twin Sticked and sitting on 35's
2010 JK- Rock Krawler 2.5" on 35" KM2's