[Buckeye30]

David. I think the patches are more likely to be 76, on the 70 / 71.
In March 1943 Erprobungsstaffel d.Lw.188 was formed to train KG6 crews on the Ju.188 ( in July); III./KG6 crews to the Staffel in Sept. In Oct. the Staffel was re-named as 4./KG66.

Only 2 of KG6's Gruppen had Ju.188s, I.Gruppe in France - Belgium, and III. in France - Germany; as Ed said training aircraft often had large letters or numbers rather than unit codes . It wasn't unusual for bombers to not mark codes on ( or overpaint them) especially for night ops.KG6 was 3E. Often the tail numbers weren't removed or used as temporary identification ( sometimes seen in Russia).
The spinner bands are either in Gruppe colour ( I.= White, III.= yellow) or Staffel colour, some bombers had both. Maybe the use of both numbers and letters was to ID the Staffel. At least one training Gruppe ( Kampfschulegruppe 3 at Cognac) had both letters and numbers on their Ju88s. Normal training units were required to use yellow markings.
Nick