What “crate loads” did the Lionel Centennial Flyer train set #6-21976 have?
The back of the box has this picture:
Those look like these:
Lionel sold them separately as Crate Load 6-12838:
They’re sculpted well. A little imagination, some primer, and a coat of paint will make these pieces useful as loads, supplies, or even just scrap in a variety of settings.