In the late 1990s, the Portland shops started rebuilding class B motors with safety cabs; The older motors weren’t such a high priority because they were more likely candidates for retirement/remanufacturing after 70+ years of service, but eventually the class B2 motors started rolling through the shops, and by 2019 most of the surviving units (with the singular exception of class leader #243) had been rebuilt. A few of them kept their original and now approaching 90 years old trucks, but most of them had those trucks replaced with class E-style trucks.

The electrical systems inside the locomotive were mainly left as-is (the only serious modification was putting a large transformer & rectifier into the B unit so the BCC4s could operate on the D&H South electrification; the old DC electrical gear was untouched because 4000HP isn’t anything to sneeze at, plus an already depreciated drivetrain is a lot cheaper than installing a modern AC one.)

In 2020, when the last two class B1s switchers came out of service, one (#239) was rebuilt into ‘class BCC5’, with a class N drivetrain and radial trucks inside a BCC4 bodyshell.

20 of the BCC4s are in operation on the eastern electrification, 4 BCC4s are in service on the South Shore Line, and the sole BCC5 is being used as a work engine on the Ontario side of the China Tunnel Railway project.