Seems the discussion got off thread with the search feature discussion
& years later, I'm ready to paint my decklid and the torsion rod hinge combo. Never did get an answer to where this little clip should be?
Given you have provided that you have a 65 Dearborn built fastback that was assigned an Oct 29 scheduled build date here are some original examples from that time period. Of course since we don't have real dates for the completion of any of these cars your car could have been built three weeks earlier or later. Because of it its more difficult to find a close match when compared to 67 and up cars. Here are some Dearborn examples I found. I held myself from using cars from other plants showing where and how far they were slipped on. Would likely result in clearer pictures but choose just Dearborn for now. Think it gives a general idea and confirmation. Of course the arms can move from side to side so the retainer does not always sit tight against the arm all of the time
Not sure of your cars VIN the pictures above range from 5F35xxxx, 5F36xxxx to a much later (Jan 65) 5F39xxxx
Pretty easy to install it as shown in the picture below - just slipped over the end and pushed far enough inward to meet the upright arm from the hinge, which given the production period would be a hinge with a dual thickness arm and a large tension rod hole for the plastic/nylon bushing
As far as leaving any area black ( in this case since the rod was black before it was installed and painted over) should not be needed since if you can see the black it should have been painted during the exterior color application. If they didn't cover well then you should have shadows on other areas also likely not just the rod