Just bought myself a Nikon FM3a/45mm lens so my pockets are almost empty. I am now looking for a camera case that will fit the FM3a/ 45mm lens, will any of the cases that suit the following fe2, fm2,f3 etc... etc fit?

Do you mean an ever-ready type case that encloses the camera?

This is from the FM3a manual-
The CF-27S, CF-28S, and CF-29S semi soft cases are available. The CF-27S case accommodates the camera with a lens smaller than 50 mm f1.4 mounted. The CF-28S is for the camera when mounted with a lens smaller than 50 mm f/1.2 to 105 mm f/2.5. When the MD-12 motor drive is attached to the camera, use the CF-29S. In addition, the CF-28A front cover for a 35-70mm zoom lens is provided.
On ebay the CF-27,28,and 29's are also advertised as fitting the FE series. The CF-7 fits the FE's too so it might fit. I doubt if the F series (F3,F4, etc..) are the same. The Nikkormats also are different. I have 2 Nikkormats and an FM3a and the Nikkormats have a longer body IIRC.
Hope that helps.

It's the one on ePay!

Surly, thats all I needed to know, thanks for the input.