To find the correct size, you should:
* Check your owner's manual: This is the most reliable source. The manual will specify the correct wiper blade sizes for your specific truck.
* Look at the existing wiper blades: The size is usually printed on the blade itself.
* Use an online wiper blade finder: Many websites, such as those of auto parts stores (e.g., AutoZone, Advance Auto Parts), allow you to enter your vehicle's year, make, and model to find the correct wiper blade sizes.
Without knowing your specific Silverado configuration, I cannot give you a definitive answer. Using one of the methods above will ensure you get the right size.