I'm currently scratchbuilding the Virginia Truckee #11 Reno in HO scale and I've hit a snag. Every 4-4-0 I've seen in HO seems to be tender driven, which really bugs me because it messes up the look of the cab. I want to make it locomotive driven, but with a 15mm inner diameter to the boiler I'm having trouble finding a motor that fits. Ideally it will be somewhat smaller than that 15mm in diameter and less than 20mm in length. Does anyone have any suggestions? I'm also not sure what kind of specs I should be looking for in terms of rpm and torque. If anyone could point me in the right direction I would really appreciate it.