There seems to be a thought that there was "a" Tasco scope line - not so. Tanross Supply Company (of Florida, USA) never owned a factory or made anything - but the owner was likely early into Japan and had Jobbers there to make his stuff that he sold in North America. They could make the cheapest garbage possible, but also equivalent to the best in the world, then. The United States Navy chose a "Tasco" product for their "shooters".
I believe the Japanese-made Tasco scopes with the silver pronghorn head on the left side, were probably one of Tasco's higher end lines - they were probably marketed under the "World Class" name - I have 3-9x40 and 2-7x32 with the silver antelope head on the left side - they are fine scopes, I think. The "World Class" line may not have been their highest quality line - I believe there was one even higher - Titan