Proceed with caution. Magneto make and model is stamped on magneto plate.
Mercury Parts Manual either on line or paper should be studies for each version
of magneto and various Mercury models to pin down what will interchange.
OR contact club member for new replacements. Old coils are very often dead coils
Same can be said for condensers and wiring. Points can often be refurbished for
further use.
Louis
Mark 20 had Bendix Scintilla Magneto
Mark 20H had Repco Phelon Magneto
They have little if anything in common.
Not many. Champion comes to mind. Early Clinton lawn mower engines are another. I have heard that some airplanes used it, but that is something I know absolutely nothing about.
The early Mercury KF-5 motors 1949′ era had the Scintilla coils you are looking for. If the coil body is cracked dont bother using it. Even with no cracks they can be bad.