CompuServe Messages

I would like to build a 3D model library so that I could quickly generate animations from "off the shelf" models. I have an immediate need for freight locomotives and freight train cars (e.g. box cars, gondolas, hoppers, etc.). But I would also like to get some of 18 wheeler rigs, heavy trucks, construction equipment, roadside objects (signs, railroad crossing gates & etc, telephone poles, tract houses, etc. The ViewPoint models are excellent but too expensive for many of the animations I would like to create. Does anyone know of any sources for public domain models that I could get for little or no expense. Thanks — Steve