Good ol' C-liners
Those old Atlas locos (C-liner, or C24-5, by the way) are really pretty much junk as far as trying to get them actually running. Trying to fix one would be fairly problematic. I suppose with some actual engineering and fabrication it's possible, but their drives aren't anything even remotely like newer locos. I got two sets (A-A, one powered and one dummy), and while the powered units did run, they were never what we would today consider "good-running" even new, and of course they're over 40 years old now.
What is extremely possible and makes for some good additions to the roster, though, is to do a little body work and make them look a bit better, then paint them up and stick a dummy unit in front of powered b-units. Makes for a very nice and quite unusual bit of motive power. While my CN paint job isn't quite perfectly prototypical, it is representative and the NYC unit is completely prototypically accurate. I'm sure there's some rivets out of place, but it's about as good as can be done with that body.
By the way, if you decide to do this, you have to do it with a dummy unit. The powered units can't be turned into dummies without the above-mentioned engineering & fabrication skills because the motor is what the front truck is attached to. No way to just take out the gears and make it free-wheeling like more modern locomotives.
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