[Bruce Parker (RIP)]

I'm looking for information on the correct material seated between CMP fenders and bodies. Specifically I need to know what was used on a 1944 HUW but am interested to know (as I suspect) if it evolved during wartime production.
My foggy recollection taking the fenders off my HUW was that there was a thin strip of impregnated fabric along the joint. I also think 11 and 12 cabs had a material folded in half such that it formed a visible round bead along the seam.

What is correct? Any help appreciated.