This saw and its characteristics provides some insight into the model that the Chinese companies used. The design by Sprunger is a good one. It is easily adaptable. The Sprunger organization is defunct meaning that patent issues are unlikely.
Harbor Freight seems to be on a quest for improved quality in their machine tools and equipment. I recently bought a Vulcan 220 Multifunction welder and I love it. Also bought the welding table and I have zero complaints. If one knows which iterms to avoid, HF is a viable source.
My examination of this machine compels me to conclude that, when it was new, it was of higher quality than my HF job.
The various machines made by Sprunger do not seem to generate a lot of criticism on the Internet. This one is still in pretty good shape in spite of the fact that it is at least forty years old and for much of it’s life it appears to have been rode hard and put up wet. The last five years saw it "stored carefully" outside in the rain.
I am happy to have this saw. When I get it to where I want it, my evaluation of it will be above the retail price of the Harbor Freight version.