See Figures 1 and 2
The 1990-96 Astro and Safari vans could be ordered with All Wheel Drive (AWD) as an option. It is only available with an automatic overdrive transmission and the 4.3L engine. The BW-4472 transfer case is an aluminum two piece unit with a chain driven viscous clutch. The AWD is automatic and has no external controls. The torque is transmitted through the input shaft to the planet carrier assembly. The viscous clutch provides the connection between the gear ring and sun gear shaft. An aluminum tag is attached to the underside of the self-tapping case bolts.