Fits most Western Star conventionals manufactured in 1986 and after. May also fit Western Star trucks manufactured in 1980 through 1985, requires part number 2991-0023 also. The CABMATE Model WSC4000 fits most 1986 and newer Western Star Conventional Tractors. It replaces the original rear cab support, Western Star Part no. RCO 66024 3414 or RCO 66024 3405. Trucks manufactured from 1980 through 1985 will also require ordering Link Mfg. Part No. 2991-0023.