You sure about that decade?
I think so, got this screenshot from early in Claremont’s Uncanny run, which started in 1975. I recently read a comic from later in that run which was from mid 1981, and I feel like that one was at least 18 issues after the one I got this from.
The art does look more like Byrne than Cockrum, but Wolverine also had his brown costume later in Byrne’s run in the '80s, so if I had to place a bet, I would say '70s.
Byrne began drawing X-men in 1977 (Uncanny X-men #108), and the brown suit was introduced in #139 (nov 1980) so 70s is definitely your best bet here. (This is 100% a Byrne panel.)
Edit: I had a hunch and found the issue, it’s from #125 september 1979, page 6 (“The perils of the Danger Room!”).
Whew, that was close! I knew something about Wolverine’s hairless arms were disco
1963 to present, according to the ‘pedia of Wiki. Yikes. I was surprised to see it went back that far.
