One problem related to steering gear box sector shaft has been reported for the 1997 Chevrolet Astro. The most recently reported issues are listed below.
There is a 1/2" metal shaft that goes into the pump that sheared off. I was making a hard right turn from a dead stop when the shaft snapped although I didn't know what had happened at the time. I only heard a noise but didn't know what it was at the time. . I lost the ability to steer and brake. I didn't know the brakes were gone until I began traveling down a hill and tried to slow down. The steering was very stiff and unresponsive. I was forced to slam the gearshift into park while traveling 35mph & using the emergency brake to stop. The pump cost $300 to replace but we have transmission damage as well with the repair bill still unknown. We had the vehicle towed.