Thanks for the history tour BM! My dad and I build many a kit from Radio Shack, Lafayette Electronics, and Heathkit.
LOL -- I found the 1978 listing of a Micronta Engine Analyzer Kit that I built when I worked in a foreign car repair shop. At that time the truck vendors all sold their own branded equipment, or you could special order top of the line Sun testers. That was way too expensive for a young mechanic's budget. This Archer Kit provided the exact same functions at a fraction of the cost. I built it over a weekend and it worked flawlessly for many years.
It was stolen when our shop was robbed some years later, but the little unit was a great piece of equipment. Wish I still had it, just to display in the garage.