Originally Posted by Bianchigirll

yes they did make both or all three, friction, retrofriction, aka "Doppler" and Synchro (lest we forget). however it can be a bit difficult to tell the difference especially if installed. the retrofriction do not have the typical 'nylon' pressure washer. if you gents like I can try and scan the parts/service catalog again.

I think the ones in rat fink's ebay may be retrofriction. and these in the pic regular friction. the most notable difference being the shape of the washer at the mounting screw.