My dad has a 1951 M that is all restored and last fall it started crunching and jerking in the rear end, so needless to say it is parked until he decides what to do with it. Does a super M have a roller bearing rear end or does it have the same cheap ball bearings as the M? We know where we could pick up a SM rear. I do like the gear spacing on the supers better, but are they any more reliable? We have owned 3 M's over the years and all of them have had rear end/axle bearing issues and two of them had patched rear ends. We have sentimental memories of the old M's and like them quite a bit, but they sure don't seem to like us!