Your photo shows the Nikon F3 with the same width as the Nikon FM3a (142mm). According to the Instruction Manual for my Nikon F3HP camera, the width of the F3 camera is 148.5mm.
I agree that the Nikon F3/F3HP isn't an especially large camera when considering just the camera body, without an MD-4 motordrive attached. Recently, I took the MD-4 motordrive off my Nikon F3HP just to have a camera that's much lighter and more easily carried. I may mount the MD-4 drive again, but it's nice to try the camera by itself again. The silky smoothness of the film advance lever is a pleasure.