CBA 24.D.2.a says:

Passover Pay Due To Junior Pilot’s Early Activation
a. In case of a junior pilot’s activation to a higher paying position out of seniority order, every senior pilot who meets the following prerequisites shall be paid as if he had activated in that higher paying position (passover pay):

1.  
   1. the junior pilot and the senior pilot(s) hold an award for the same crew position; and
   2. the junior pilot’s award is from the same posting as the senior pilot’s award or from a subsequent posting; and
   3. the Company chooses to activate the junior pilot prior to the senior pilot(s) and the junior pilot’s activation delays the training and activation of the senior pilot(s).

Obviously the rub is over the very last phrase (isn't it always?). The Company holds that if you are doing different training (e.g. ITU vs Differences), then by definition your training hasn't been delayed. The presumptive ALPA position is that since 767 ITU is simply 757 ITU followed by differences training, the senior pilot has in fact been delayed. I actually think we might win this one!