Well, it's still evolving.
Aviation Technician(AVN) was MOC 514 which was formed by merging 511(AE), 512(AF), 513(Avn Snr NCMs), 531(SS), 551(IE,many went Avs also) and 572(AWS).
Avionics Technician(AVS) was MOC 526 which was formed by merging 521(IS), 525(CRS), 525(Avs Snr NCMs), 551(IE, see...