the parts plants (Rawsonville, Sterling and the new Hot Metal Forming department at Woodhaven Stamping) still have the old 2nd tier scale, and once people start transferring/retiring out of there, it will only be those lower paid workers.
Good luck with another tier, especially at the Assembly plants. Most people hired before the beginning of the 2015 contract are still upset about the whole 2 tier thing. A third one won't pass.