To explain here, the M29 Thomas heavy tank in this article is the T29 heavy tank in history. In this timeline, due to the butterfly effect of the old horse, the T29 was stepped up testing and completed and an order was issued for construction. T is the US military tank.
It was a test code name. The official name of M will be issued after it is officially entered into service. Therefore, the T29 was transformed into the M29, and was named the M29 "Thomas" heavy tank after the famous Civil War general "George Henry Thomas".