I picked up a single motor Rocket last year and just assumed someone switched out the twin motor chassis for a single one. Just checked the date stamp on it and it shows as March 1955. So what did this come with as a set then?
Here is a picture of the business end of the reverse unit.
Lower yellow goes to a brush, black next to it goes to motor field, red on top goes to motor field, two blacks to left of red go to reverse unit field and the other one goes to front power chassis and is soldered to top of unit which is power pick up, wire pick up from rear dummy truck goes to other reverse unit field which also has the green with it which is the other motor brush.