The FAA lets pilots fly any model of the 737 when there is not much similair between the 300 and 900 models. They also let us fly the 757-200 and 767-400 and there is nothing similair about those. There is two ways of doing it: common type and dual rated. CAL is planning a dual rated, like the 757/767. It's two separate types, but pilots fly both and recurrent training will be one night in a 777 sim and one in the 787 sim. That's what I'm hearing from 777 instructors in the training center, but we'll see what really happens.