I replaced my */C coupler this weekend -- I reinstalled mine just as in the photo below -- and its how the factory original had been installed; but I saw in some other locations it should have been the oppostie with the flanges toward the base.

http://www.bonnevilleclub.com/forum/...osedrive+stuck


I have worried about it since seeing it installed both ways and didn't want to have to take it back apart; but it smoothed up the */C and she whirrs away quietly how it is. Any cause for concern? I couldn't understand any possible reason it could cause a problem; and the original held up 8 years

It makes no difference. The 'bumps' are just spacers to fill the gap between the pin plates. The inside chamfers are only to ease installation.