Here is a brand new Rimfire V (3/8-24 thread) modern-day replacement for your old Champion V and similar spark plugs. It is dimensionally the same outside except for the hex, which has been reduced to 7/16 instead of 1/2. Not only does it weigh about 4 grams less, it is engineered to increase compression and run hotter than the old spark plugs from the early days. The ground electrode is machined rather than welded so there is no chance of stripped threads.