what fuel pressure gauge will work that i can mount inside the car. also i see some that run about $95 then the same ones but full sweep for $188 whats the differance?

 

The low $$ AutoMeter gauges are 2-piece - a sending unit and the gauge. The gauge needle has a 90-degree sweep, and the marking are (if I recall correctly) 12.5psi apart... 0-12.5-25-37.5-50-etc. Hard to read accurately.

The high $$ gauges are 3-piece - a sensor, an electronic interface box, and the gauge. The needle moves a full 270-degrees, and the markings are every 2psi, so they are much easier to read accurately.