Well, I got close with the Atlas motor, but ended up swapping the entire thing out for a new Tomix drive. The friction in the OEM trucks and drive train was just more than I could overcome with a new motor. I pieced it together into the plastic frame of one of the trailer cars, so now it's got a completely new drive train.

I used the Tomix motor mount, which nested into the frame nicely, but caused the motor to ride a little high. This made the drive shafts a wee bit too diagonal and created some friction going around the tight bends of the layout. My friend Randy Gustafsen fine tuned it for me, and it runs great now.
The only original equipment from the drive is the zinc weight, which I have screwed to some styrene blocking. I put the original side frames onto the Tomix trucks, which fit surprisingly well. It sits just a hair higher than the trailer cars, but not enough to affect coupling or clearances. Given the simplicity of the Tomix drive, it would be dirt simple to put a decoder in it.

And, as I mentioned, it runs like an absolute champ now. I think there's an opportunity to breathe new life into these models. The carbodies lasted quite a while in the real world, with a couple of different configurations, the later ones had the mechanical blister above the roof line. But the distinctive cab end remained the same throughout. I'd love to see an updated version using the nice Budd tooling that Bachmann did for the latest round of Amtoobs.

Next I'm going to try to coax my E-60 back to life. The old 3 pole motors in them are terrible, and of course, it suffers from Cracked White Gear syndrome... I'm going to start by substituting a Life Like 5 pole motor from an old GP18, then see where we go from there.
Lee