I can verify that it goes back to at least '71.5 then. Forget what month mine is, but it's got the Dana 44 and the fuse block in the glove box. Non-CA truck too. Originally sold in Montana. Or at least the first owner was a Montana hunting ranch. It could have been bought in CA. Think it has a code for Fremont in the VIN, but it's been awhile since I looked.
And I bet more were removed by PO's than you can imagine. Not just on Fords, but anything that was owned by a "tinkerer", or was serviced by an old-timer that didn't like extra stuff to screw with. Saw more than my fair share of them go straight into the garbage just because they were some of that "un-necessary crap" that nobody wanted to bother to take the time to adjust, or to even understand.
Paul