1952 Ford F1 Door Glass Install

[Eagle43]

I'm in the process of reinstalling the glass in my doors. I thought I had purchased everything to complete this task but I am stumped by one thing. I don't have anything to put in the channel on the division bar opposite the vent window. I purchased from LMC and they don't seem to sell any weather stripping to fit in that channel. Anyone know what's supposed to go there for the window to slide through? If I remember correctly there was nothing in there when I got the truck.