Thanks!
That's surprising. I've owned three ADs and none of them had that - not even the strip that holds it. Maybe it was an option?
Nope. That lower windlace was original equipment on all '50-'55.1 AD trucks. Earlier years also had them, but they were of a different style which were screwed into the side of the rocker panel, rather than through the top like in your picture.
This windlace seal is necessary to make up for the highly variable fitment of the door at the bottom where the door seal is compressed so tightly by the retainer that it does not seal much, if anything.
Carl