My brothers OTS, vent code "D", has the clips and the same twist pan with the folded edge.
Let's see the vent pic please
My bad, it's actually an "E". I can get pics but I won't be near his house until the weekend. I got him some parts for his bday and he said he was cursing me the whole time he was drilling out the ash sweep for the new one, lol. Now his grill is clean again for the first time since '83.