Great question, I believe all you need is the controller SN according to the activation page.
http://activation.knifeedge.com/RealFlight6/
All you need is your G3 Interlink with serial, and the RF6 upgrade disc, and you're set. You do not need to have a prior version of RF installed.
All you need is your G3 Interlink with serial, and the RF6 upgrade disc, and you're set. You do not need to have a prior version of RF installed.