Two problems related to structure have been reported for the 1999 Chevrolet Silverado. The most recently reported issues are listed below.
Rear sliding window frame cracked allowing water to enter vehicle and flooding the entire passenger compartment. It has been leaking for some time and is not noticeable until the water starts seeping from under the carpet once the padding is soaked. With the heater on, all of the glass becomes fogged which will impair visibility unless you put the windows down. The padding and carpet has also caused a very bad mildew smell. Dealership refuses to repair and states gm will only cover less than 36,000 mi. Its most likely the crack occurred before 36k with so much water under the carpet but now at 57,000 its just noticed. Gm must be aware this is a manufacture defect, but like myself there hoping most consumers with this type of vehicle won't notice the problem until after the 36k mi .
Rear sliding window frame cracked in three places, leaks water into cab. Replaced once under warranty with same plastic frame. One year later two cracks already. $275 after market window has metal frame. Called gm will not help with any of the cost. Door seals also leak and make noise at highway speeds.