Nikon PB-6 Rail End Caps

[sciolist]

I acquired a Nikon PB-6 bellows secondhand. It was delivered without all of the screw-in plastic rail end caps whose purpose is to prevent components from sliding off the rail accidentally. While these caps might not be strictly necessary, I'd like to know if anyone knows of a supplier who has them. Nikon has advised they're obsolete and no longer in stock.