For anyone interested, this is part one of the 2 lens systems that Nikon developed which by changing the rear elements could be changed from a f8.0 360mm to a f11.0 500mm to a f16.0 720mm lens. I own the 500mm/720mm combination. The 500mm is really quite good. I have not had the opportunity to use the 720mm. I do not have the 360mm in part because I already have a Rodenstock f9.0 Apo Ronar.
Presently there is only 21 hrs, 30 min left in the auction. Only 2 bids have been made and the present bid price is only $537. Reported condition is "fantastic".
Anyone in need should certainly consider this lens, particularly if you want a 500mm tele lens in the future (you have to find the rear elements to swap however).
Rich