As a follow up:
Looked at it today. Still not sure the manufacturer. The GM guess is still probably a good one.
Somewhere along the way the stringers, floor, and transom were redone. However, the transom is already showing flex cracks at the corners; of greater concern is the stringers. They are un-treated lumber run longitudinally, and at the time tabbed in - not encased. They are no longer secured to the hull. I could actually move them back and forth within the taco-shell glass work. There may not be lateral support either and the floor had significant give. I think it may have been 1/2" ply.
The hull was flexing fore-aft such that the skeg had curvature.
He said the previous owner was a fisherman who did the work with a boat-builder friend. I'm skeptical of how many boats this friend had built.
Overall a good project boat, as long as the buyer knows the work needs to be redone... properly this time. It's got a very nice galvanized roller trailer under it now and he only wants $1250, though after my assessment he would probably let it go for whatever the trailer cost him.
