I'm talking about models, not "real" trains. They're motors and gears must be precisely matched, otherwise. the unit with less traction power it will slow the other down. I'm still waiting for the FT-B unit to arrive, it is powered and analog. There are a couple of wires coming out from the A's motor terminals so its decoder will drive both motors. But I'm serioulsy considering stripping the B from the motor and gears and leave it as a dummy B unit. I have F7 A and its dummy B unit and it pulls the freight train effectively. What would you do?