I have tried a polyclonal by MyBioscience but it cross reacts with CX43. I currently have the 1G6A7 clone that seems to be popular but have not had much luck with western blotting with it.
the Calreticulin Antibody #2891 - Cell Signaling Technology works very good. Maybe you will see two bands. The lower band is possibly representing a stress-induced isoform (unpublished results).