Tom Foss has done a lot of research and hands on work with RC's. There are more than just a few differences including a made for RC only flywheel and radiator which is longer than a B/C one. I've seen many of these differences on my machine.
At the bottom is a link to Tom's site with loads of pics.
Hope this helps, Joehttp://home.comcast.net/~old_allis/ac-RC.html
By the way, post a pic with serial number. Thanks This post was edited by mdtractormechanic at 14:01:26 12/17/12.