This one has a late OG 8xx serial number (my guess 1970 or 71?). Rough picture, but this would be a hog top / flat back, yes? Thanks....
All
flat-back D25's have 'hog tops, including the Corona re-issues and GAD's.
The arched back version started being phased in in '72, still with 'hog tops, and by far the most common year reported for those is '73.
The spruce top version was being offered by '74 and overlapped with end of the 'hog-topped production if dates of examples seen on the net are accurate, and I've seen one 'hog-topped archback reported by an owner here from '76, probably a fluke or leftover, maybe?
Think it's actually a '70 if it's still using the OG-type s/n.