Jim Carter wrote:
Can the glideslope tracking be added as an option or does that involve some
tearout and throwaway if you don't purchase the feature during original
install?

Not an option for the 30. The 55X will fly both ILS's (LOC & GS) and
the WAAS glideslopes. If you were to upgrade, I don't know how much
of the original installation is recyclable. You would think that
the servos ought to be in common.