Later cars have a U shaped rubber seal fitted to the body edge here along entire length both sides.
Interesting! How does the U-shaped seal work between the round chassis tube and the flat wooden body frame? A photo would be great if you get a chance... My car has rubber U-section seals between the bodywork and inner chassis in the area near the battery tray.
Apologies - I was looking at the wrong side!!! Yes you have the rubber seal fitted as well...seen many an m3w with this seal missing.
The way the later body is mounted does reduce this issue - I assume your existing 6x body mounting screws are tight?
