Any update on if the issue still persists after repair has been made? We have had this happen two separate times for a total of 4 occurrences total. Our local Chevy couldn't replicate the issue the first time and told us "nothing is wrong, feel free to drive the vehicle as normal." The second time it happened, it locked up the brakes at 75 MPH and put us in the ditch and flat spotted our rear tires. Our local Chevy couldn't replicate the issue again, but said yeah you need a valve body, feel free to come take the truck and drive it until we can get the part....interesting. Opened a case with GM customer support, but seems like they are just as difficult to work with as our local dealership.