two railing the r142?

i'm thinking gears and electronics

 You might ask Joe from Baldwin Forge as maybe he's converted these? I bet if the trucks are the solid type, the wheels are a pain to swap out. Once that's done, you would just need some kind of electrical pickup like wipers or plungers on the insulated wheel side.

I converted an older set.  In short, it will just take new wheels (insulated and uninsulated) pressed on to the existing axles and pickup wipers fabricated.  

For my method, I have variable configuration a wheel puller to remove the old stintered iron wheels.  You will reuse all existing axle and gears.  Find the right wheel size, (source I've used are P&D hobby bare wheels) bore to the correct axle diameter on a lathe at NYSME.  Press on to the trapped axles.  There will be a bit more axle length but for trucks with side frames, it should be ok to leave it on without shortening the axle.  Then take the wire from the red pickup rollers and fabricate a wiper pickup system on the insulated wheels.  PS2.0 using the 3v battery and above operate fine on 2 rail DC so you are free to keep the electronics.  You will even be able to do the conversion without cracking open the body shell.

Another option are the NWSL 4 or 6 axle conversion kits.  They use new axles and they are for powered truck blocks only.  

Really dumb question:  why would you want a 2- rail model of a 3- rail prototype?

Thanks for the input guys, glad to know it can be done somewhat painlessly.

Bob, I only run 2 rail dcs and I love modern subways but mth does not offer them in 2 rail. For a railking model it seems well detailed. though I'm sure extra detailing would be likely.