It is a friction fit between the draft tube and the filter canister. The canister is then firmly held in place by a bracket that fastens to the bell housing via one of the mounting bolts. That mounting point stabilizes the whole assembly. I thought I saw this posted earlier, but I guess not.
Imperialists,
In my postings I was using the wrong terminology: I should have been using the word flared, not flanged, concerning my two piece '56 lower draft tube and how it slips into the breather device near the tapered end of the draft tube. It does look stock to me nonetheless.
Respectfully,
ybshore