727 Locked up while driving causes?

@d55Dave... WOW! That is something else! Bad! I'am no trans expert, maybe I'd be ranked a novice. But looking at my service manual it seems the only way that could happen in park is if fluid leaked past the manual valve enough to pressurized the reverse circuit. And then revving it caused reverse to engage. But can that blow past the parking pawl? Maybe so for the same reason you can take it out of park while on a steep hill. Man,I gotta ask. Parking brake set? I always set em. All the way. Without even thinking about it. Sure messes up some people if they use a car after me. Hell,my belvedere doesn't even have a park. Must use parking brake! Hope you made a complete recovery! WOW!