I have a Nikkor 20mm f2.8 AF.. dont remember off hand if it is a D or not.
It is dissasembled and sold for parts only.
I purchased it as-is with part of the front filter ring broken off. It would not focus to infinity, so I thought it had been a botched repair. I dissasembled it and re-assembled it a couple of times. I think I found the problem, it looks like a tab is broken that controlls the close-focus-correction. The unit is complete except for one of the 3 screws on the lens mount is missing.

The glass is in great shape. and it would otherwise be a very nice lens. So I really dont want to re-assemble it. if you want me to re-assemble it so that you know where all the parts go, I can do that for an additional $25.