Most of the original release #76 Buffaloes (1965-1991) are some shade of Brown - veering from near Black at one end, to Buckskin/Dun at the other. The Red Chestnut ones are something altogether different chromatically, enough to make you think they were a separate and distinct release. I haven’t seen any evidence that this is the case, though. They just happened to make the #76 Buffalo this color for a while. (The Elk and the Moose, too. Neither one of those is on my want list, yet.)
This particular example is one of the redder and less shaded ones I have seen.
Other than being a newer rather than older piece, I’m not entirely sure where the Chestnuts fit in the Buffalo’s variation chronology. To give you an idea how complicated that web of variations is, the Buffalo behind "Red" here is an early one with nostril and lip liner, yet I also have another early one with a Small Blue Ribbon Sticker (ca. 1966-67) that is very matte and very much on the Buckskin side. There doesn't seem to be any logical progression or evolution.
Dealer and Collector’s Manuals from the mid-1980s onward do show more "chestnutty" Buffaloes, for what that’s worth. The overall quality of the paint job and the seams would be consistent with this, so I'm content with pegging it as a late variation, for now.