Interesting to note my GM Camaro parts book dated Aug/74 shows only 1 trim ring for 1969 Z28 - # 3901708. Then a later issue GM Camaro parts Book dated Sept/75 shows - # 9796696. No trim ring attaching style notes are included in either parts book description.
My GM Chevelle Parts Book dated Apr/76 shows the # 3901708 trim ring as - 2&1/2" wide -Attaches with 4 clips, fitting 74-76. It then also shows # 9796696 as a supplemented part number for this ring.
Then it shows # 9796696 fitting 70-73 Monte Carlo and it says - Approx 2&1/2" Wide - Attaches with 4 Clips.
I do know that later issue # 9796696 trim rings had the serrated teeth or fingers and were still available from GM I think until approx. 2007? There is also 2 versions of this ring, early issue had Black Serrations and the later issue had Silver Serrations. I have a NOS set of the # 9796696 and the boxes are dated Mar/2000 and they have the silver serrations.
My personal opinion is that the # 3901708 - 4 clip style trim rings were the original line installed trim ring on the Z28, and the later issue # 9796696 trim ring with the serrations was a mid 70,s service trim ring, and was also used by the dealer to replace existing 4 clip trim rings after that part number # 3901708 was superceded to # 9796696.
Jerrys Book only mentions that 2 styles of trim rings were used. No Offence meant but I honestly don't see how a legends judge could comment with certainty that in or around Feb 1969 they went to the fingers all the way around the ring to stop the 4 clip design falling off, when the Early dated 1974 GM Camaro and Chevelle parts Book do not show the Serrated type trim ring.