Set contains additional lower shells to fit different applications: For engines up to 1994 use lowers: M 480L1 X 1, M 480 L X 2, For engines 1994-1995 use lowers: M4018L X 1, M 480L X 2, For engines 1995- 2004 use lowers: M 480L X 1, M4018L X 2, M41
