plastic piece that slide into back bar

I think we can help, though we'll need a bit more information. Primarily, I'd like to know the size of the opening that accepts the track. Once I know that, I'll see if any of our sockets match up.

It's also important to note that all of our sockets mount to the back of the drawer using screws. You mention that yours installs using a slot, which is not something we can help with. You would have to find a way to get one of ours to screw to the back of your cabinet.