Odd piece of plastic at top of door opening

[Bmachine]

I am installing new rubber trim around the door. The big 3 part piece that goes all the way around (#8 on diagram). As I was ready to glue the top section, I noticed that there was a piece of hard plastic that was glued to the aluminum trim (7 on the diagram) that is screwed on the body work. The rubber gasket was then glued on to that plastic piece. It looks like a custom fit part which nestles nicely in the "slit" on the aluminum section. But since it occupies that space, the new gasket which has a cut out groove ready to fit into that slit has no place to latch on to.

Has anyone seen that before? Is this a '74 addition? My car was repainted by the previous owner so it could be something they added but it seem highly custom fitted to be a backyard mechanic job.

 

[Bmachine]

I am tempted to just remove it but wanted to make sure it isn't a know part that is supposed to be there.

If it was, I would have thought it would be on the parts diagram but maybe this is a late addition...

Rearmost end:


Front end at bottom of A pillar:



New gasket with "groove" on left side that should go into the "slit" in the aluminum piece #7

 

[Bmachine]

Actually, I think I may be answering my own question right here. After looking at the previous rubber piece that I had removed, it seems that the PO installed a two-part piece. First was the hard plastic that latched onto the aluminum trim and then it was a mating rubber piece that was glued on to that. really strange because it looks like a completely non-Bmw part. It was obviously custom made to work in that section.

 

[bavbob]

It should not be there, not original to the car. Installation along that alum strip is difficult so perhaps either it is there as part of the two part non-OEM thing or just to make it easy to install (straight glue). I would remove it.