The piece for the "A" post is about 2 feet long while the one for the "B" post is about 10 inches long.
I double checked my 1958 TR3A yesterday and all 8 ends have been tucked back inside the hole on the central rubber tubing for a neat appearance.
For the "A" post it goes up the door and bends to follow the curve all the way to the top end.
I seem to remember that the "original" pieces for the "A" posts were glued to pieces of masonite about 1/8" thick and about 2" wide all the way up - before instalation to hold it all nicely while you are trying to insert the tiny screws through the carpet, then the hole in the masonite.
The grey piece along the inside of the inner sill is made of aluminium. This trim covers the area shown in the photos above and is a flat alum. piece witha vry nice smooth curve where it goes ober the vetical flanges where the inner and out sills have been welded together. I can't find the part number but - if you're interested, I have a brand new set but they are made of shiny stainless steel. I bought them but never used them because I wanted my TR to be as "original" as I could get it, so I bought others in aluminium.