You say What..?

[nachoman]

With the motored truck removed, and all wires disconnected between it and the chassis, take an ohm meter and test continuity between the wheels on the power truck - if there is, the motor is hardwired to the truck and may be difficult to isolate. Or, take the disconnected truck and put it on the track and see if it will go. If it will run - the motor is hardwired tot he truck and may be difficult to isolate.

Being that this is a "pancake motor" chassis, it would be difficult to simply remotor with a can motor. Your easiest option may be to find a chassis with the same wheelbase, and put the shell atop that.