 The second in the series is the W3B 050, which was released initially for the W116 450 SE and SEL in 1973.At that time the four-speed transmission for the 350 SE and SEL was replaced by this three-speed model.The reinforced W3B 050 reinforced (type 722.003) is the strongest of the series, able to handle the input of the enlarged version of the Mercedes-Benz M100 engine, the biggest Mercedes-Benz engine in post-war history, exclusively used in the W116 450 SEL 6.9.