I already had a look at the 3dinfo information, but in case of 3dAnatNudge, I can see only something like "3dAnatnudge -verb -anat brain+orig -epi epi+orig -prefix nudge", but not the actual translation parameters. Furthermore, I am not quite sure, if 3dAnatNudge does something else like setting the origin to zero etc... For the nudge plug-in, it is easy as you suggested to get the information.