Mike, Kudos, Glad you got Full Points for the trim rings !!
This debate about the different style trim ring has been going on for years, and will probably go on.
I personally think the 4 clip style was the assembly line installed trim ring when the Z28 was assembled and the full serration type was a superceded/updated design trim ring. I don't honestly know how #9796696 serrated trim ring could have been used in 1969, that part number never even showed up until the 72-74 GM parts book. BTW 67 Corvette used the same 4 clip trim ring and the GM parts book for Corvette shows the #9796696 trim ring as the superceded number for the 4 clip trim ring.
JMO of Course.