We have a 06 Cummins 48RE, it has a random hard jerk between 50 and 62 mph
It may happen 5 times in ten minutes and it may not happen in a hundred miles.
It's at the dealer for the fifth and maybe last time. They've flashed the computer several times believing that will fix it. It's been at 2 different dealers and a transmission shop each time with no codes or faults showing even when it happens.