Outstanding, thanks! (and merry Christmas)

My grandsons lost the track power wire for their ez command system. I have some wires intended for the dc connections from the ez track system that have spade connectors on them. I got a 3.5 mm plug from radio shack and thought I would just make a new one. Can someone tell me which leads of the plug I should solder the wires to? I know the tip (left channel) goes to the small lead, the center ring (right channel) goes to the medium lead and the shank (ground) goes to the large lead. Which two should the track power wires connect to? I thought about plugging in the jack and checking the leads out with a voltage tester but not sure how to interpret the results. I'm an extreme novice when it comes to the electrical side.