It's part # 6(Bulkhead Body - ARB-170605). It's the bulkhead that goes through the diff casing. #8/9 is the steel line that runs inside the diff.
From all accounts the outside thread is 1/2". the ID thread is from all accounts (Measured with my calipers) is 5/16". However part #5, which threads into it, (Central Compression Nut (5mm to 3/16") - ARB-170604 states that it's 3/16". Perhaps i am off on what i should be measuring?
In any event on part#6, since i went with the braided SS air lines, i thread into this part
- 2 ARB air locker fittings
- Axle fitting is a -3 AN male flare with compression seat for use with ferrule on opposite end
- Solenoid fitting has a -3 AN male flare with a straight thread and O-ring seat on the opposite end
The inside thread of the bulkhead was all stripped to hell. Now i see why the previous owner had a massive amount of goop on the fitting end that stuck out of the diff.... I don't know how that helped though as it was leaking inwards as well.. Fawker...