One problem related to noises during shifting has been reported for the 1999 Chevrolet Silverado. The most recently reported issues are listed below.
Other equipment; severe vibration that feels like body flexes between 65-75mph. I have slowed and pulled off onto the should fearing personal saftey. I have brought it to 2 dealerships for a total of 5 times, and spoken with gm customer service, as well as written a letter to Chevrolet. They claim that it is a new "charateristic" of this year, no fix. Powertrain:transmission:automatic - it shifts into overdrive at about 37 mph producing a growling sound, brought to two dealerships for a total of 5 times, no fix. Other equipment - clunk noise from front.