Nikon PB-5 Bellows

I bought a 105/4 Bellows Nikkor lens (2nd version). It is coming to me with a PB-5 Bellows. I already have a full PB-4 outfit. When I looked at the PB-5 manual, it did not show a focusing rail as an accessory. Did Nikon or anyone else make a focusing rail for the PB-5?