You ought to get some royalty money for that photo.
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Prince Edward Island
'64 Parisienne CS "barn find" - last on the road in '86 ... Owner Protection Plan booklet, original paint, original near-mint aqua interior, original aqua GM floor mats, original 283, factory posi, and original rust.
JonathonD's pic certainly provides an excellent visual reference of the interior roof. Royalty worthy for sure.
I have been studying the black art of headliner installation and came across a U tube - 2 part video with a 70 Chevelle that is receiving a headliner. The installer speaks about how important it is that the rods are re-located back to their originals holes and marks each rod as to where it came from in terms its original location from front to back.
This video might not be of any assistance to help in deciphering which diameter rod goes where but perhaps you might find some value in the video. Definatley not a 68 Catalina, but it is a 5 rod bow headliner and there are some similarities. Maybe it can help you out a bit.