The smallest pylon was only capable of being loaded with rockets. A slightly larger one (Mk 55?) was then introduced that could carry both rockets and small (100-lb?) bombs.
This AD has the small pylons with 100-lb bomb capability as well as one large AERO 14A pylon that could be loaded with both bombs (up to 500-lb) and rockets.
Note that strictly speaking, AERO should be all capital letters, since it is an acronym for Aircraft Equipment Reference Ordinal...
