I think they may be more recent than 70s, due to the wording printed inside. A close up of the full bottom sole and heel would be helpful. If there are any markings on the soles, that helps, too. Made in USA really may narrow it down enough to figure out, with additional pictures and date range narrowed, who the maker is. Also, D is primarily a width associated with Men's shoes. Do they seem like a women's 8, or more like a 9 1/2? Unfortunately US sizing isn't non-binary, so that will require actual measurements, if you are planning to sell. It's not an official term, but I like to call these types of boots "Shit Kickers" cause they are not fancy, totally sturdy, no sewn pattern, and have a chunky heel. That's not a riding heel. But, they are every-day-wearable.