The older kits had a smaller vertical stabilizer and non counter balanced rudder. I think in the newer kits they went to the bigger vertical stabilizer so the parts are common with other kits. I fly an older RV6 with the smaller vertical stabilizer and it flys fine.
I think in 1996 or 1997 they started selling the bigger rudder and VS with the RV6 kits. I finished mine in 1997 but I bought the tail kit in 1995.Did they begin selling the RV9 rudder and VS with the later 6 kits?