727 Locked up while driving causes?

In 34 yrs of working on torqueflite's I have seen all types of carnage but I have never ran across one doing what your describing. I wonder if it's something real simple like the parking pawl rod came unattached from the VB and is trying to apply the pawl?? That's the only thing I can think that would cause this. Would be real easy to tell by just dropping the pan.