Hmm... I dont know. I have only 1 photoe of Me410A "Gelbe 7" from 6./ZG 26.
Another proof of M8+ code of ZG 76 in 1944:
Hauptmann Johannes Kiel, standing near Bf110G-2 from 7./ZG 76.
Look in area near his sigarette, to right from it. You can see small letter "m" on the fuselage, the first letter of "m8+?R" code.
http://pics.livejournal.com/bersrk/pic/00005w95
Best wishes, Evgeniy.