Bought a used RKS FP45 a few weeks ago (PS2/3v, or so I thought) and just had a chance to try on the new layout I'm building. It starts in reverse with the front headlight lit, and no rear headlight. I found that very odd. This AM, I opened it up and it looks like the previous owner converted to PS3, but left the rear lights disconnected from the green connector - it was in the right place, just disconnected. And they had the yellow and white wires for each motor connected backwards. Yellow to white. White to yellow. The most troublesome item - soldered connections used black electrical tape folded onto itself on all 4 solder joints, and the black electrical tape had fallen off each connection - 4 joints nearly touching each other. Surprised I was able to run it without short. I reversed the motor connections, connected the rear headlight, and it works exactly the way I thought it should.
I wonder if the person MU'd this engine as the second engine while double-headed and always wanted it to start in reverse.
Anyway, happy that it worked out.