As to the ZG 76 second installment.
III. Gruppe used
2N+ code...but its formation has never completed (9th Staffel never existed).
Stab, I. and II. Gruppe ZG 76 were having code
M8+ !!!! Photos showing a/c with other than this are from the months of late August 1943 and September, when unit was in phase of becoming new or used a/c Bf 110 and in training mode. Since October all a/c had proper marking with M8+ letter code..in January 1944 lettering was abandoned at the unit and digits in Staffel colors were used, e.g. M8+ black 2. For the Bf 110 the
M8+digit was used, for the Me 410s
M8 digit + format was used (number ahead of fuselage cross)
Hope this helps....(information based on photos and Flugbucher/documents readings