The -N is the 116 HP version (8.1:1 compression), with the -L having 8.5:1 for 118 HP @ 2800 RPM, with the original prop limiting them to a bit lower RPM and power output (108 and 110, respectively). The stock high compression (9.7:1) 125HP versions are the -F, -G (conical mounts) and the -J (dynafocal mount). The AirMods STC essentially makes a -L into a -J using stock internal parts, with the additional AirMods prop STC allowing the full 2800 RPM (but the Senenich STC for the same prop does not).
As the -N is also a dynafocal mount, it could also be converted, but do not recall if the STC covers those.
