In March of 1981, class B2 #251’s rear unit had one of its trucks spontaneously disassemble when it was hauling a freight between Portland & Albany. After the wreck was cleared, the Portland Shops decided to rebuild the front section into a pocket B+B motor as a possible replacement for classes 240 & 320, and this newly trimmed unit was back in service by fall of that year.

As a replacement for the switching motors, it was a failure – crews didn’t particularly like the high deck or cabs – but it found a nice niche as a slug parent or power supply for slug-capable diesel units.

No further units were rebuilt into B2As – in 1987, B+B steeplecab #598 went into service with a much more positive reception from the crews– but #251 continues to operate (with a multisystem drivetrain that was fitted in 2005) as a booster/rotary snowplough motor into 2024.