Thanks for the heads up on the K-mart and ShopKo. I picked upa few more tractors at the local K-mart, and plan to raid other nearby K-marts and ShopKo's ASAP. As far as the Norscot models go, most of the HO line seems based on the smaller Cat models, and not the large size models. For instance the Norscot D5M is on the lower end of the scale that runs from a 70hp D3 to a 850hp D11. The D5 is only 121hp. The D8 is one of the more popular Cat models (I work at a power plant that has D8 and D11 bulldozers). Again, the 315CL excavator is classified as small on the scale that runs from a 54hp 307C to a 513hp 385CL. The 315CL is only a 110hp model. My photos show 325's and 330's as popular flatcar loads. I do have one pic showing three 320CL's on a 89' flatcar.
As far as the Norscot Mini stuff, they do seem to be HO scale models of some of the miniturized CAT models. Not really suitable for flatcar loads, but great for a residental construction site. Comparing E-bay pics to the model spec page at cat.com, Id' say that is exactly what those are.