Have you tried checking the Thomas Register web site? They have models for standard parts available from quite a few manufacturers there in a variety of formats, including STEP.
I checked them out too. I found some DIN conns (if I recall correctly) but no 3D Models
EDIT: When in doubt, do it again! I just rechecked Tyco, and lo and behold, they DO have 3D part models. Awesome! Now, if I could just get it to import correctly.... :?