I think Whodo and Kiwi are referring to Nikon TC's that fit between mount and lens (not in front of lens front element).
In which case I believe they are correct. DX lens aren't compatible and may result in damage if used if the rear element of the lens comes in contact with the lens elements in the TC's. Even compatible FX lenses may loose some AF functionality when the effective max aperture drops below f8, except on the the newest AF systems in the D4/D800 that do AF down to f8.