As I said in my ten wheeler thread, I recently bought the cheapest Lionel "General" ever made: the Redwood Valley Express
engine. I bought it to bash it into a 1/4" scale 4-4-0. As I cogitated over my ten wheeler cab, the idea of simply relocating the motor and gears of the General came to me. It turned out to be quite easy. The first photo is for reference. It shows the original motor and gear tower. Note that the frame extends well beyond the rear drivers. The motor is centered behind the center window post in the original cab.
I drilled holes in three of the drivers, to pop off the spoke inserts. (Don't ask me why it doesn't show in the first photo; it's very much there.) This is necessary to realign the cranks, and it also facilitates drilling and tapping the cranks. Beyond that, it proved a fine way to access the screwed-on gear plate for removal. That's why the hole in the rear driver is larger; it allows a screwdriver shank to pass through it. The near-side frame has a similar hole on both sides of the axle.
My new plate is roughly the length of the cab, with allowance for the front and back walls. (Interestingly, the stock plate is the same width, leading me to think MPC may have been considering their own "General" scale modification at the time they designed the can motor re-powering.) The motor is centered, so its armature shaft will be right behind the center window post - as on the stock version. The plate is a bit less tall than the cab will be, as I cut it even with the motor top. The idler gear will extend into the boiler. I run tested the new configuration, and it's as smooth and quiet as the original.