I have a 2023 GMC Sierra…
I have a 2023 GMC Sierra 1500 AT4 w/3.0 diesel. 33000 miles. Tranny started slipping so went to a local Chevrolet dealer. Their transmission guy said 2 solenoids are sticking. He relayed it was a common issue and has killed a lot of transmissions. The parts are backorder with no timeframe. Could be 2 months could be 8 months. Seems odd they have parts for new trucks but not for warranty.