Since Feb 2003 737s have been produced with the Collins EDFCS-730, this is fail operational, has an optional rudder channel and is Cat IIIb certified. I presume that these aircraft are dual-dual, even if the previous aircraft were not.
We operate a mix of Collins (Cat IIIb) and the earlier Honeywell (Cat IIIa) 737NGs. The photo was taken of a Honeywell equipped aircraft and I have seen these on a couple of other Honeywell aircraft since. I am now wondering if these fittings (pretty sure now that I can’t call them aerials) are on our Collins equipped aircraft.