Isn’t Jr the only player in NFL History to be on three straight SB winners (2 with Dallas, 1 with San Francisco).
There have been lots of players who were on three straight NFL championship teams, i.e., the players who were on the 1965, 1966, and 1967 Green Bay Packers. They just didn't call the NFL championship game the "Super Bowl" yet. And those last two Packers teams did then go on to win the first two NFL vs. AFL "Super Bowls."
You could even include the players on the three-peat championship teams of the 1929, 1930, and 1931 Packers, as well.