Yes, that was a typo. The first time I wrote it, I got it right... goofed in the next sentence, which I've now fixed.
If you've looked under your engine and the black and red wires are visible going to the motors, then yes: One red wire from one motor truck gets connected to the black wire from the other motor truck. Like I said, you'll probably want to ditch the white terminal board and go with small wire nuts, so the brown and blue wires can be properly placed again. Unless you're good with a soldering gun. Then you could loosen the white terminal board and reattach the wires, and then use a piece of double adhesive foam tape to put back the terminal board.
Then if you want to get creative, I use an E5 socket with a mini T 1-3/4 bulb for headlights. I used to get these from Radio Shack. Now you'd probably have to find them online. The T 1-3/4 bulbs come in either 6 volt or 12 volt. With the motors wired in series, probably a 12volt bulb would be best.
I use a piece of craft foam (available in various thicknesses from Hobby Lobby or Michaels). I use the foam to make ties for my 027 track, and for scenery, so I keep the foam on hand. I remove the headlight lens, then glue a small piece of the foam on the inside of the shell, right over the headlight opening. Then I use a small screwdriver to make a hole and I insert the bulb into that. The foam helps with any heat generated from the bulb, and I've never had any shell damage from this. You'd connect the bulb leads to the brown and blue wires. But I'm handy with a soldering gun. Actually I solder alligator clips to the bulb wire leads, covering those with a clear piece of drinking straw as an insulator, and clip them over my ground and hot engine wires.
You could also go with an LED, but you'd need one that is prewired to run off AC current and one with a somewhat flexible voltage range.
