Yep. 3.B.6. I think, around 15 years ago. A.K.A. "The Hammer" which is one of the reasons LM thew money at the pilots; to help that mighty provision go away.

IIRC while C2K was the "UAL+" contract, its often forgotten that the UAL part of that equation was a beneficiary of the "Delta Dot" which was basically the 737"NG" pay negotiated when "The Hammer" was still in DALPA's hands. UAL patterned off of that to get their pay tables which became the "United Plus!" rallying cry for C2K.

There was also a 777 kerfuffle around that same era where DALPA called LM's bluff ($500/hr in 20 years ago dollars was the rhetoric, but who knows what was actually in the negotiating room) and he threatened to park the fleet but did end up cancelling orders because of it. Once the dust settled DL only had a micro fleet of around 8 of them.

Regardless, it was a very powerful provision that is now gone.

Which is why IMHO we won't see "757 pay"...because 757 pay already is 767-300 pay. That is only because it is a common category. I doubt any arbitrator will put the 321NEO in the 767-300ER pay range.

That's why the 737-900 (AKA the "other ER"...don't be h8'n) which came after "The Hammer" was given up only pays a dollar more than the -800.