I installed used axles that had ARBs already in them and had a heck of a time finding just the blue line and the fittings. I think they are made specifically for ARB or maybe it is an Australian thing.I think Tarhell 4wd in charlotte has some but I ended up getting on the ARB web site and getting the phone # to the US distribution center and calling them. They were alot cheaper. The US ARB center will not sell you a locker or a compressor but they will hook you up on small parts and send you exactly what you need quick. Hope this helps.
Not sure exactly what fitting you are looking for but I would try Pirtek on W. Market at Dolley Madison or Alliance Hose & Tube on S Elm at Industrial.