GM launched a new C-body of advanced design for 1948 Oldsmobile 98 and Cadillac, but Buick did not adopt it until 1949. It was designed by Frank Hershey under Harley J. Earl, and was sometimes known as the 'P-38' owing to its inspiration from the P-38 aircraft. But for 1950 Earl oversaw new B-body and C-body designs which featured a waistline than dropped down over the front door before rising back over the rear wheel arch. Ned Nickles gave the Buick its 'ventiports' a dummy ventilation hole that appeared on the front wings of Buicks, 3 for the cheaper cars and 4 for the top of the range models. Also in 1948 Buick announced the Dynaflow automatic transmission for the Roadmaster model, but this was so popular that it was given to cheaper models and became almost default. The Buick Special was built on a 121.5-inch GM B-platform also shared with the Oldsmobile 88 and Pontiac Chieftain, whilst the more expensive Buick Super and Roadmaster were built on a 121-inch GM C-platform shared with Cadillac and the Oldsmobile 98. Buick introduced a 2-door hardtop body in 1951 on all its models which was entitled 'Riviera', and from 1955 there was also a 4-door Riviera option.