Replacement parts for swivel seats

[MCF]

I need to find some new plastic slides (do you call them bushings?? - the things inside the slide tracks) and the black collars that are inside the seat base - where they clamp to the posts. 2-7/8" posts. It's a 1999 18' Sea Pro Center Console.

Anyone know where I can find parts? Or similar seat bases at a decent price?

Thanks!