Common sizes found in that year's Silverado 1500 include:
* Doors: Commonly 6x8 inches or 6.5 inches. Occasionally, you might find 5x7 inches.
* Dash: Usually smaller speakers, typically 3.5 inches or 4 inches.
The best way to know for sure is to physically measure the speakers in your truck or consult a repair manual specific to your year and model.