If front drive shaft goes through the rear worm, that means that the rear drive shaft has to be hollow. Very interesting idea. I hope on some future visit we can take some photos? Of course, if I showed up with a good camera and a light tent, you (or, more likely, Linda) would wind up having to throw me out after some number of days (ha -- or hours!).
And, although the 24-hour news cycle on the Overland 2-8-8-2 is long past, here is another photo:

The model is pulling a long coal drag on Michael Ross's big Virginian layout. It's not a great photo of the locomotive, but I post it so I can follow with this one:

The model is pulling only 0.5 amps while pulling itself and a good size train. I show this as a back-door way of pointing out that the engine has a Doug Cockerham drive in it. I don't have any data on other articulated locomotives to know if this low current draw is really unusual or not, but the drive is quite smooth and seemingly quite efficient.
I have one other example of UP steam, which I will post next time
Jim