Wow, that is kind of cool. After thinking about it a little more, I am just wondering who Henry Nelson's supplier of glow plugs were. I wouldn't think that he would machine all those plugs for us idiots (me included) that burned them out from too lean of runs. Just guessing for every engine that Dub and Nelson sold, and now Profi, there had to be at least three or more Nelson plugs manufactured and sold. This could be quite cumbersome on a single guy working a machine shop making engines and plugs.