Catastrophic transmission failure while driving on highway trip with family. Thankfully did not completely lock up drive train, but such a catastrophic failure could have caused a transmission/engine lock up leading to a serious accident. Drove to nearest Chevy dealer (Everett Chevy Morganton NC), inspected, validated catastrophic transmission failure. Vehicle towed back to Hendrick Chevy Monr NC. Hendrick confirmed catastrophic transmission failure, required complete transmission replacement. I requested failed part evaluation/warranty review. Escalated to Chevy customer support. Hendrick replaced transmission 1/29/2025. Hendrick upgraded to new Thermal Bypass Valve per service bulletin #21-NA-199 as part of complete transmission replacement. Vehicle was serviced previously on 11/1/2025 for routine oil change and inspection, with transmission noted as ‘good.’ Onstar monthly diagnostic for December 26, 2024 indicated engine and transmission system ‘good/OK’.