I'm looking for some help finding replacement hardware for some 1960's(?) kitchen cabinet drawer slides.

I've looked at all the local & box hardware stores, as well as many ****** distributers with no luck.

I've never seen drawers like this with rounded bottoms (see pictures below). There are several of them missing, and because of the way the cabinets and drawers are constructed, there is no way (good) to change the type of glide.

They are made of nylon, and if anyone can tell me where to get replacements, I'll be very gateful!!