Part Type: Serpentine Belt. 1989 Western Star 3800 Engine: 10L L6; Position: Fan and Idler;. Position: Fan and Idler. 1990 Western Star 3800 Engine: 10L L6; Position: Fan and Idler;. 1991 Western Star 3800 Engine: 10L L6; with 59in Long Belt; Position: Fan and Idler;.
