Hi Rick,
Using the nifti_tool prior to 3dmerge did work though I'm still not sure why my other zstat.nii.gz image was already in the correct format and this one was not. Is there a way to evaluate the sform codes from the nii image? In a related vein, I'm curious as the interpretability of my results after changing the sform code. When I load the 3dmerge output into Afni to visualize the 'Where Am I?' option works but is it accurate (did it actually transform the data or did 3dmerge just not recognize it correctly)?
Thank you again for all your help,
Rachel