1994 F150 window water in rocker part 2

my attempt at diagnosing my water problem getting into the rocker when there is heavy rain.
I set up a hose pointing to the outside of the passengers side door window.
it would appear that the gasket that seals the plastic and rubber for th door closing vent is rotten and needs to be replaced.
F150 1994 OBS water leak
they don't sell these parts or gaskets on rock auto or that I can find. so I'm going to have to make my own gasket.