Ah, the cover of Bad News!!
I looked last nite & thought black motor 77/78
There was several styles over the years.
Variances I noticed were in the notch area behind the case numbers.. top bolt area. I think some used a washer or case guard, and some did not.. also a difference in that fat post in the middle of chain run area.. some had the rubbery sleeve over it and some I think did not.
Noticed something odd on a 78K recently... the sprocket cover was nearly impossible to get out it was hitting. surprisingly the owner who had several other covers, did not file the cover, but rather the filed away on the frame..

On my 836 I have cut the lower bolt area off, only use the 1 bolt, real easy to get the cover off..