This is what i got for the fuel pressure gauge, it goes into the test port, this is a cool set up gets the sender away from the heat and viberation of the motor.
This is there new web site same place just a different name
6.0L Fuel Pressure Adapter
I'm running Autometer 0-100 i just ordered the gauge less the adapter fitting because the fitting comes with the hose.
If you get a fuel pressure gauge and your pressure is low this is the fix.
Mine before i installed the fuel pressure gauge i had 50 lbs at idle and 44 at WOT
and that is to low, installed the kit now 62 idle and 58 WOT
, low fuel pressure will kill injectors and over 70 lbs may blow injector o-rings.
The Reg. Kit number is 3C3Z-9T517-AG and you get it form Ford
The spring is located behind the small plate that the return line attaches to. This is probably one of the easiest repairs you can make... Take the four screws loose (they are T-27 torx screws), change pull the old spring out of the brass cup, put the new spring in and re-install the plate. When you are taking it loose, keep your thumb on the plate so the spring/cup doesn't pop out and also use your thumb to hold the plate up tight to the fuel bowl when re-installing, so the screws can be threaded in good. If you buy the whole kit (which I think is the only way you can get it from Ford), I would replace the brass cup while you are at it..
You can see the plate and return line here.
Page 30: Fuel Supply System
The only hard part is the hose is in the way, you need to get a turkey baster a new one and suck out all the fuel from the upper filter houseing that way you don't have a mess. After you are done you have to cycle the key 3 time 30 sec. each time to prime the fuel system.
Here you go this is a post by Band Member on the fuel pressure reg spring install over at the Dieselstop
Fuel Regulator Upgrade w/ Pictures - Diesel Forum - TheDieselStop.com