I saw that ad also. I had one of those back in the late 80"s that I purchased in an estate sale. It was a neat looking rig but had a chatter. I called Tesoro about it and they said that they had never seen one but if I would send it in they would tune it up. I sent it in and several weeks later I got it back with the meter blown out and a note telling me they didn't have a replacement,,, which was a bunch of baloney,, thee was nothing wrong with the meter when I sent it to them. I suspect they put it on a bench power supply and blew it. (the older unit used a 9 volt battery while the newer ones used higher voltage).
Sooo much for the tesoro sob story,,,, if you go to buy it make sure the meter works and it isn't the one that I sold in a garage sale for $5.
PS, I was told by another person later that it looked like one that Tesoro made for Montgomery Ward back before Tesoro changed hands