The Pfanstiehl magneto setup is very unique on Fuller & Johnson engines.  It is not shown in any catalog or mentioned in any known factory literature.  The forked bracket is part number N124.  The large center boss held an idler gear which was the same size as the governor gear.  This was driven by the cam gear and in turn drove the magneto gear.  Unlike other gear setups F&J used this one slid right onto the straight magneto shaft and was held in place by a taper pin.  The magneto itself is unique as it did not bolt to the engine via a baseplate like most other mags.  Instead it has a boss turned on either end of the bearing plates and sat in a forked bracket.  This bracket was pinned at the bottom end using the hole regular reserved for the cam gear guard bolt.  A pair of caps captured the magneto's mounting bosses, the rear one having a tab on its top.  A steadying rod screwed into the hopper and its opposite and lined up with the tap and was secured with two nuts.  An advantage to this highly unusual mounting style was that now the magneto could be turned about its axis to fine tune timing of peak output to the ignitor.  A pair of tabs just above and flanking the central boss provided a way to affix a somewhat elaborate cast iron gear guard part number N141. 

    It is possible this magneto and bracket was initially intended for the People's Priced line.  Many of those engines have an L shaped nub with a drilled 1/4" hold cast onto the back of the water hopper.  This lines up nicely with the bracket's rear cap.  Although I have yet to see any real world evidence that this setup was actually shipped on a People's priced engine, there also not being any indication that magnetos were ever offered with that short lived series.  This particular example is original to a 4hp N Kerosene from early 1915, the steadying rod merely screwing directly into the back of the hopper.