Shuckhardt was the first that I know of. But he wasn't the only. Both Patrick Henry Omlor and Hutton Gibson likewise were early traditionalists who possessed exceptionally brilliant minds and quickly came to the realization that true popes could not possibly promote heresy to the entire Church. A large number of people who never went along with the Novus Ordo at any point, ended up sede. And now even the Novus Ordo people are reacting to Francis not by asserting a right to reject his doctrine but by going directly to the argument that he cannot be a true pope. Salza is the poster-child for everything that can go wrong when you take the R&R position and then arrogantly assert that any other position is heretical and/or schismatic.