I've always used gaskets on my insulators. Underneath the insulator, I've always used one of the really old asbestos gaskets, as I had a bunch of 216 ones. On top of the insulator, there always seems to be a paper gasket in the kit that works fine. I've never actually put my foot to the floor, I just downshift and enjoy the scenery!
The screen looks like a back fire spark arrestor screen.
Or maybe the truck lived where there were lots of those mud dauber wasps!
