I see that Ford started making the Cruzin' wagons in '77.  Can my 76 be adapted with the panels to make one, and what all needs to be done?  How are these attached on the 77 and later?  Can I just put these panels over my windows?

My understanding is that the body structure of the wagon area was carried over from year to year. Case in point - I had a regular '79 wagon, to which I attached the panels and created a panel wagon much like you desire.
You first need to remove your original side windows and any trim around them (if present). The panels are attached to the body with a number of "tabs" on the panels through which screws can be driven between the pinch weld areas of the original window frames and the panel tabs. The panel surfaces need to be sealed against the car with 3M body seal.
This is a general guideline; I know thah there are other factors (like gutter extensions, interior panels, etc.) that also are part of making these panels 100% "factory appearance", but the attachment of the basic panels themselves to the body is pretty straightforwar d.
Good luck!
Chris

Thank you all for all your info!

Looks good, I like the rims!