This is a project I have been working on for a very long time. So many experiments - from motors (originally started with Pullmor motors) to trucks to fitment to redoing the CNC spanners. But it's all said and done, at least for this iteration 
. Runs and pulls like a champ - I have ~20 hours on it now. It's a bit of a nonsense model of but I loved doing it. My next plan is to make an A' unit to house a much bigger/better speaker, and in turn add a bit more brass ballast to the A unit (luckily I had the foresight to have a duplicate frame and spanners fabricated). I also want to find a paint match for the where I had to remove the sides (luckily only visible with the engine upside down as shown). I was going to do something custom with the shell but at this point I've kinda run out of steam so I'm going to shelve that for now.
Stats:
Shell: Williams E7-A with custom fixed pilot (sits too high though), F7 rear steps and some random coupler with shoulder bolt (doesn't look great but it works)
Frame and spanners: Custom CNC (got the idea for the truck spanners from the Lionel 6518 transformer car)
Trucks and related items: Lionel postwar GG1 (NOS from Lionel, which I opted for owing to traction tires)
Motors: Timko GG1 DC retrofit motors (notice I had to shim the motors at an angle to preload the worm gear against the worm wheel in order to mitigate gear skipping)
E-unit: Dallee 1400 (x2)
Sound: Dallee Hi-Line
Performance: Weighs 10.0 lbs, runs on O-54 (amazingly) and larger, drawbar pull of ~6.0 lbs (which is about the max continuous draw on the motors) but approaches ~7 lbs with the aforementioned replacement of the speaker with add'l brass ballast
Cost: Like any decent project WAY WAY WAY more than you'd guess, esp. if I include the experimental parts and pieces mentioned
What I'd do different: I simply used spray paint for the frame and spanners and it didn't take very well - should have done something else. That's about it...
