2002 Chevrolet Silverado transmission problems

Vehicle rolled back while in park. Truck was found against the house with the doors locked and still in park. Emergency brake is typically engaged because it is parked on a slope drive but it was found disengaged. While being towed it also rolled while loading onto the tow truck. Again, it was in park with the emergency brake engaged. Vehicle was looked at by two separate service departments with no cause found.

Dt: the contact stated while driving on the interstate there was severe vibration . He drove slowly to the dealer for inspection while the vibration weakened at a reduced speed. The dealer performed a diagnostic test that produced a code involving the automatic transmission. Upon further inspection, the extension housing of the transmission cracked and was leaking transmission oil. No repairs were performed by the dealer due to the extensive work and expense.