Lawrie.. Re the Diff cover plate, I went to the Thrift store and bought an old Aluminum fry pan, the right Diameter, and cut the rim down with a scroll saw; to the right size and hammered it on a block of wood to dome shape it slightly, made up some clips (3) to hold it in place, painted it then when I was ready to make it permanent I sealed the edge with some asphalt sealer, looks good and is sealed JMO..