I'm looking to replace the gauge unit on my fuel pressure gauge (as in keep all the fittings and hoses, just replace the actual gauge part). I'm not sure if I need to look for something special for fuel. I've looked at McMaster-Carr and I'm sure they have something that will FIT, but most don't mention any sort of restriction (fluid only, air only, etc). Does this mean most of them are compatible with fluids?

The gauge looks something like this...

Here's a trick I learned from an old friend. I used a five dollar tire pressure gauge from any FLAPS(usaully reads from 0 to 60 psi I think). Just unscrew and replace the tire valve brass fitting with a new threaded brass fitting for your application. I've done this for my fuel pressure gauge on my turbo rotory motor setup. It was reading a healthy 35psi and never failed. I currently have a tire pressure gauge for a fuel pressure gauge on my v8 setup, too. Just my .02

Interesting!!!