Welcome to The Gauge John.
I have an MDC boxcab that uses the same drive. I replaced the primary gearbox with a belt drive, which quieted it down and reduced the overall top speed.
I removed the gearbox, made a new driveshaft that connected the worm shafts of the two trucks together using an Athearn SW 7 driveshaft with a pulley from an old tape deck pressed over the slotted coupling. An Athearn drive belt was used to run from the pulley to the motor.