WARNING: This page is about a different car, the 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: 4.3L VIN X, A/T Circuit
Fig 2: 4.3L VIN X, Transfer Case Circuit, 2-Speed Automatic
Fig 3: 4.3L VIN X, Transfer Case Circuit, 2-Speed Manual