May I suggest 2 sites to check:

www.whatever3d.com is a search engine for 3D content.  It will scan the most popular sites for possible hits.  RDNA has recently undergone a site reimagining and many links are broken.

www.sharecg.com is content site for freebies.  You might get lucky enough to find something worthwhile to suite your needs.  But you must register and it's free.