This may be the final word. Went to Allen Mello Dodge in Nashua and tried to order the cover for my 2007 SXT. They printed out this page, and here is the quote.
" The engine cover has been deleted in production for the PM49-Caliber, MK40-Compass, MK74-Patriot on all packages equipped with the 1.8Ls and the 2.0Ls engines. DO NOT order a replacement cover if the vehicle arrives off the hauler with no engine cover and is equipped with a 1.8L or 2.0L engine. This is NOT a shortage or error and is NOT a warrantable repair. The 2.4L high-line vehicles still have the engine cover released. The 2.4l cover should only be used on so equipped vehicles"