Shortly after the six-axle variants of the Dash 7 series, GE also introduced the B23-7 in September 1977 as the first four-axle variant. It was the successor of the U23B and had basically the same V12 variant of the 7FDL with 2,250 hp. By 1984, a total of 523 had been built in the USA and 13 by GE do Brazil. The largest customers were Conrail with 141 and Nacionales de Mexico with 122. Ten more with a large crew cab were built for the Seaboard Coast Line as BQ23-7.
Three months after the B23-7, GE introduced the B30-7 as successor of the U30B. It was still powered by a V16 with 3,000 hp. Of 399 which were built between 1977 and 1983, 120 were cabless units. The largest customers were the Burlington Northern with 120 and the Southern Pacific with 82. After the Missouri Pacific had received three B23-7 in 1980 whose V12 was boosted to 3,000 hp, most new-built B30-7 also got this engine that had a reduced fuel consumption compared to the V16.
After the V12 had been brought to 3,000 hp, the V16 was brought to 3,600 hp, what led to the introduction of the B36-7. With only four axles and that much power, these were well suited for fast intermodal and container service. Later production batches even had 3,750 hp. In total, 230 were built of which eight went to a coal mine in Colombia. In the USA, the Seaboard System was the largest customer with 120, followed by Conrail with 60.
