I've just run the SS air hose from the engine bay to the rear diff, so here are a couple pics of the install for those interested.
I used the Rubicon Express 12' SS Air Hose, and was super disappointed because instead of including two of the same fitting, the one pictured here (AN/JIC -03 Flared Male to BSPP -02 Straight Thread) they include ONE of these and another AN/JIC -03 to Flared Male to AN/JIC -03 Straight Thread. Basically this fitting doesn't exist in industry, and I ended up having to purchase an ARB fitting (AN/JIC -04 Flared Male to BSPP -02 Straight Thread) and a reducer (AN/JIC -04 Flared Female to AN/JIC -04 Flared Male).
This is moot for most people because they'll probably just use the crappy push-to-connect plastic hose, but I hate that stuff.