I've found plenty but in other formats. I scour the free 3D sites like Sketchfab and BlendSwap. There's also lots of 3D pirate sites that host a ton of that stuff. Frequently the files are shitty conversions of .Max files. Otherwise I import them into Blender, fix what's needed then export them as .obj files for import into Studio.
The 3D pirate sites come and go I just grab a picture of what I want and do an image search. I usually get lots of hits in these sites.
For a legit source, try the 3D section in RenderHub.