Looking for help making simple reverse units

Bill, Not a reverse unit, but take a 8 or 10A bridge rectifier.  2 leads are AC in, and 2 leads out are DC  + and -.  Take the DC out to a double pole double throw switch at center taps.  One end wires to the motor for forward, and the other end is reversed to power in reverse.  Move switch to desired direction.

Or buy a DC or AC reverse unit from Lionel, MTH (BRU), Williams, Dallee, etc..  Easy AC in and DC or AC out to motor.  G