Mike,
Good question. (see two posts up)
The ADSB out Tailbeacon actually goes into the WHITE LIGHT on the rudder and not actually on the RED beacon.
So, it IS on the part of the rudder that moves...technically, they have to do it.
However, I am very skeptical a device that weighs .5 oz more than the light will have ANY affect on a plane that is now 43 years old, has over 8,000 hours, is bent 6 ways to Sunday, and gets 85 knots on a good day....meaning I will pay to have the work done and certified, but it will not make ANY difference in flying the aircraft!
HERE is a diagram of it as it would be put into the rudder cap facing the 6 o'clock position of the aircraft...