Threads on fuel rail?

[Sleeper-6]

Just got a rail mounted fp gauge today, but I'm wondering what kind of threads are on the end of the rail. The gauge is 1/8" NPT, and that definately looks different than what's on the car.

 

[U1ARUNIT]

You will need an adapter from AN or JIC threads(taper) to 1/8" Pipe threads. I *think* the rail return side end is a -4 AN size. Most TR vendors have them or you can find one at a local fitting/hose supply store.