I noted in the Chuck Cantwell book he mentions that early in the 66 builds (15" wheels) they had front tire contact with the fender like the 65's.
The story in the book was they specified convertible front coils on later DSO's. Is there DSO documentation of this change?
It appears the fastback, hardtop "GT", HiPo, "66 HD" spring C5zz-F was #1413 lb rated with red paint stripe,
the convertible GT, HiPo, A/C spring was C5zz-E # 1491 lb rated with brown stripe.
Later they replaced the F (red) with the E (brown).
regards,
jim p