G'day all, I have drained my fuel filter and replaced it, on my 150 d4d, but for the life of me, can't see where the guard on the bottom is supposed to line up with a mark... can see the mark on the guard, where is says "caution" line up with mark on the lid? Where is it! Anyone have an idea?.. is it necessary or important? What's it for? Any thoughts or suggestions please... even if your name is Mark.. cheers guys.. Odog