Overdrive and lockup solenoids rarely fail. You will need to put a pressure gauge in the OD check port at the rear of the case to verify pressure. A scan tool will also be needed to verify that the PCM is commanding OD. Without doing this you are just guessing. If it is commanding OD and you have no pressure you most likely have a bad OD piston lip seal or missing check ball in the rear support/OD piston retainer. You can drop the valve body and air check the OD piston operation. You will need to make some sort of plate to cover the rectangular supply hole on the VB side of the case with a small hole in it to apply shop air. If you look closely you can see the operation of the OD piston through the case where the park rod goes into the OD housing. If there is a problem with the OD piston seal, it can be repaired with the trans in the truck and removing just the OD housing.