Thank you for your kind comments, much appreciated
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Afaik, the mysterious "White chevron and 81" is likely due to a misinterpretation. Both 61 and 81 are in fact the same A/C. If you look closely at the skins of these aircraft you'll notice that their camo's are identical indicating they are the same with differing tac numbers. As far as the typo is concerned, colour profile (Think it's by Jerry Crandall) shows number 81 on fuselage and 61 on the wings - baffling isn't it? However, when looking at the image on "Walk Around FW 190D No 10" publication and even more clearly at an image from google, it's clearly a 61. I included the version 81 as an option "just in case".
(Note the unorthodox wing camouflage pattern).
Of course one can speculate if the code number 61 was later replaced with 81, but IMO the image above proves this is not the case. Anyway, I hope this helped. Bear in mind I'm an amateur aviation historian at the best and there may well be more info out there than what I can gather. Thank you for your interest in this subject and happy flying.