On the fuel bowl towards the back is a O ring boss(ORB) plug. My fuel pressure sending unit is a 1/8" NPT. Pull the plug and take it to a hydraulic shop and get an adapter to 1/8"npt. I believe it is a -2 ORB to 1/8"NPT, could be -4 ORB to 1/8"NPT. Maybe get both and return the one you don't use.
Early 99 (Born on 11-20-98) F350 CC LWB 4X4
north of 480hp and south of 13.7sec
Bored with current setup