Here's some of the early MX designations from 1941-1945. I've been going through the AAF files at NARA II for an Osprey New Vanguard on US Guided Missiles of WW II. The list isn't complete and I need to add and correct some designations. BTW, many if not most of the early MX designations referred to sub-components such as auto-pilots, servos, flight control systems, etc.