Retainer, Jack Base (P/N 3929976, Group 8.820).
In 1968, the retainer was for all SS Camaro convertibles (including SS 350 engines), excluding those with space saver wheel spare tires. Here are the relevant 68 AIM pages: L34/A2.5-10E; L35/A15; L48/A2-10E; and L78/A3-10E.
In 1969, the retainer was for any Camaro with either the RPO PW7 (i.e., Tires; F70x14, 2-ply white stripe, original equipment) or the RPO PW8 (i.e., Tires; F70x 14, 2-ply red stripe, original equipment) tire option, excluding those with space saver wheel spare tires. Here are the relevant 69 AIM pages: L35-L34/A3-10E; L48/A2-10E; L78/A3-10E; and PW7-PW8/A1.
The new 67-68 Camaro Legends Judging manual includes a photo of the retainer on page 131.
Bernie