To find the exact towing capacity for your specific 1990 Chevy Silverado, you need to:
1. Locate the vehicle's sticker: Check the driver's side doorjamb or the glove compartment for a sticker listing the specifications, including the Gross Vehicle Weight Rating (GVWR) and towing capacity.
2. Consult the owner's manual: The owner's manual should have a section detailing towing capacity based on different configurations.
3. Use online resources: Websites like Edmunds or Kelley Blue Book may have some general information about 1990 Silverado towing capacities, but you still need to know your truck's specific configuration for accurate data.
Without knowing the specific trim level and engine of your 1990 Silverado, any number I give you would be a guess and potentially unsafe. Always rely on the information provided by your vehicle's documentation.