Joseph Donnelly
TDR MEMBER
2003-5 had aluminum top and bottom halves to the valve cover, with a plastic trim cover for the crankcase vent/filter on top of the cover. In 2006, they went to a plastic one-piece humped cover with a 1" thick aluminum plate over the head and under the cover. The electrical connectors are in a 1/2" thick plastic piece sandwiched between them.