AC44C6M rebuilds have been done by GE (now Wabtec), American Motive Power, Inc., and Norfolk Southern Railway's Juniata and Roanoke Shops, starting in September 2015.

The AC44C6M retains the 16-cylinder 7FDL-16 prime mover used in the core locomotive prior to rebuilding, but replaces the Dash 9's DC traction motors with alternating current GE 5GEB13B7 traction motors.

Externally, the rebuilds have received new wide-nosed cabs, a new front hood section, and a new inverter cabinet behind the cab, while retaining the underframe and engine and radiator compartments of the original Dash 9 units.

[5][6] These were followed shortly by Norfolk Southern's AC44C6M's, which were first delivered at the end of 2015, and rebuilt from their Dash 9-40C locomotives.

Norfolk Southern's AC44C6M locomotive features a new under-floor air conditioner, cab signals, LSL (Locomotive Speed Limiter), DPU systems, PTC, and ECP braking ability (on some units).

A Canadian National AC44C6M rebuild was spotted outside of a Wabtec facility in early September 2022.