How do I switch the skin of objects that have multiple skins?

Not materials as in the material tool, but actual skins. I remember a skin switcher tool in GM12 but I can’t find anything for GM13 that works. I don’t see anything about switching the skins in the C menu either.

I’m trying to switch the skins of some cars from the TDMCars mod, and I was able to in Gmod 12.

Use the bodygroup changer tool.