Mack Parabolic Leaf springs: R/RS/RL/RD 1965-1990; CX Vision 2000-2005; CH 1988-2003; F model 1975-1988; U model 1975-1991; CV/Granite Model 2002-2006; RWL/RWS Models 1988-1975; FL/FS/WL/WS 1975-1985