I have been collecting American Flyer for a long time. I know that the Greenberg guides list a 336 with a small motor and a large motor. However, I have never found or seen an "original", non-modified 336 with a small motor. I have checked with other notable collectors and have received the same response from them. The 1952 K335 did come with a small motor. Since these motors can be switched, I would not think it would be unusual to find a 336 here and there with a small motor. Someone could make the switch and sell the large motor separately and probably make more money with a separate sale of the 336 and large motor. If anyone can verify that they have or have ever seen a documented original 336 with a small motor, I would be interested in hearing about.
Ken Orlowski