Here's why:
* Many Options: Chevy offered a wide variety of axle ratios in the 1990 Silverado, depending on the truck's intended use (work truck, tow vehicle, etc.), engine size, and transmission.
* No VIN: The Vehicle Identification Number (VIN) is the key to determining the original factory specifications.
* Possible Modifications: The previous owner may have swapped the rear axle at some point, so it's not guaranteed to be the original one.
How to find the gear ratio:
1. Check the VIN: The easiest way to determine the factory ratio is to find the VIN and use a decoder website or contact your local Chevrolet dealership.
2. Look at the Differential Tag: If you can access the rear differential, there may be a tag attached that lists the axle ratio.
3. Measure the Driveshaft Rotation: This involves marking the driveshaft and the tire, driving a short distance, and counting how many times the driveshaft rotates for each full tire revolution. This method can be more complex.
Most Common Ratios:
For a 350 engine and 5-speed manual transmission, common rear axle ratios in 1990 Silverado trucks included:
* 3.73: Good for towing and acceleration.
* 4.10: Even better for hauling and climbing hills.
* 3.08: For better fuel economy, but less towing capability.
Important Note: Knowing the gear ratio is crucial for things like tire size selection, performance, and fuel economy.
I recommend you try to find the VIN or the differential tag to get the most accurate information.
