Based on 4 cut cross sections of Trunk seals and fit, I have found that the 1A auto trunk seal lays down in the gutter the best and seals properly. These are better fitting than what GM was selling in 1982. In Video you can see how well this conforms to the trunk channel/ gutter.
https://www.1aauto.com/1970-81-chevr...36/258266/1973
video here >
https://www.youtube.com/watch?time_c...ature=emb_logo