I just got a brand new Nikon D750 body. However, I found that the package has a lot of room to move around so I don't know if there was any damage done to the camera body during the shipping.
When I move the camera back and forth from pointing the camera upward, then downward, and repeat, I can hear some "ticking/clicking" sound caused by the movement. It sounds to me like some internal part (i.e. a lens/mirror inside the camera body) is kind of loose and have room to move about inside the camera body, and slightly hitting the surrounding (my hypothesis).
It does seem to take pictures fine. So I am curious if other D750 does the same and have the similar noise from movement.
I did try similar to the other two DLSR. Nikon D5000 makes some noise but the noise level is much much fainter. Olympus E520 makes even smaller noise which is almost negligible.
As an update which may be helpful for future users:
I went to a local camera store, and their D750 also has that slight "thing-shifting-inside-the-camera" sound, he said it's normal so I think I am at ease.