If it was an automatic car, the wires would have powered the shift indicator light. If it's just a pair of wires, that's probably what it was. If it was console wiring, it would have 3 female plugs. Back-up light wiring would only be present on manual trans cars and would go through a hole in the tunnel. As Mid. says, it would be black wires with a dark red stripe.
There are some places to look on the body to help determine if the car was a 4 speed. The location where the speedometer cable comes into the car is unique and there would be a hole on the passenger side toe board that is used to secure a clip to hold the cable up.