Lense for Nikon fm 2n?

Would a nikon 50mm nikkor f/ 1.8 af-d Auto fucos lense fit in a Nikon fm 2n film camera?

Yes, the nice thing about the Nikon system is the "F" mount has not changed even as they moved into AF and digital. Just make sure when you use older lenses that they have "AI" auto indexing.
Enjoy.

It will work 100%

if you have any questions about lens compatibility, refer to this handy, dandy chart:
http://www.kenrockwell.com/...y-lens.htm

As long as it has an aperture ring.

The FM-2n is all manual and needs to set the aperture on the lens itself.

Just remember that whichever lens you use, the body isn't capable of autofocus. The 50mm f1.8 AI, AIS or Series E, all fit this camera and are available used at much lower prices than the AF version.