I'm planning to install a NARCO 121 NAV unit in my Maule. My avionics tech says
to "make sure it has the 'M' mod". Anyone know how to tell if this was done
without opening the unit up?

George Patterson
God grant me the senility to forget the people I never liked anyway, the
good fortune to run into the ones I like, and the eyesight to tell the
difference.