Beginning in 1954, the Hydra-Matic 4-forward-speed automatic transmission is available in the Chevrolet Suburban (GMC offered this transmission in 1953). In addition to a transmission upgrade, the inline 6-cylinder engine was increased in size to 3.9L. Models with rear panel doors were designated "3106," while those with tailgates were designated "3116." The front bench seat was split, with two seats on the drivers side and a single seat on the passenger side, which slid forward for access to the rear two rows of seats. The second row was a "2/3" seat, requiring occupants to move past the front passenger seat, as well as the second row seats to access the third row. This was the last series to feature "Canopy Express" models. The design of the 1949 Suburban would go on to inspire the design of the Chevrolet HHR over half a century later.
Source: Wikipedia, 2013