The OX would require extensive custom modification to the front of the axlebeam, and to the OX's diff cover.
I've heard of several problems with stubborn or inop shifters on them too, yes.
As for the ARB and problems with moisture and freezing weather, I can't comment on that myself being in So. Calif, but I would think with as widespread as they are in use, someone would've had that problem by now, but I haven't seen anyone comment about it (moisture shouldn't get into the air lines anyway, as long as the air solenoids are not at the bottom of the compressor tank).
Something I've noticed, the small ARB tank dissipates it's pressure slowly over a few days, It seems that's enough to keep water from accumulating in there (the moisture evaporates and is expelled out with the air).
