Not sure. Every Bronco from mid-70 on up had the evap canister, so I'm thinking that DSO didn't matter on that particular component.
I recently found out that many full-size pickups did not have evap even up to about 77 or so. Which was a real surprise, since I thought all the light-duty pickups got the same basic smog stuff.
Apparently not, but the Broncos have all had it that I have seen.
Does not mean that there were not exceptions of course, and maybe someone can tell us if their original from '71 or later did not have the stuff.
Paul