Hi Marc,
Kracker says NAGr.6 and the following paper says NAGr.8, clearly. (third pic.)
https://www.ebay.de/itm/Papiere-und-...75.c100623.m-1
Since I'm not sure NAGr.6 had Bf109 but Me262 & Bf110s (according Holm's site) I'm just thinking he first flew with NAGr. 8 then NAGr. 6.
But I know nothing about him. Hope someone has an answer.
Regards,
Franck.