GM differentials, C clips and clutch v. cone lsd's

[My68SS]

Hi all,
When did GM drop the usage of 'C' clips in Camaro's? I've read in another forum that they were still in use in '72 Chevelles.
Apparently, most Buick, Olds and Pontiac diffs were not C clip design.
Any breakdown of the usage of C clips across GM differentials and GM vehicles appreciated.

Also, any info on the usage of clutch [Eaton design?] versus cone lsd across the range also appreciated.