It is a
Sears sold bike, from right around 1976. small bike in the middle, the 80757 woud indiacate its actually from Sears, I dont know if they were made by or just another vendor but a company called ARA offered that odd line of bikes them as well at the same time and they called it a Trail scout. It was a short lived line of bikes, and you only see them for like a season or two, The ARA sold version form their 1976 catalog and below it is the 1976
Sears catalog (where yours came from) is below your engien configurations show like possibly 1975 build, it will be hard to get the numbers off it though due to the corrosion, they will be stamped across the top of the engine shroud up by the headbolts:
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