* 3.50: A relatively common ratio offering a balance between fuel economy and acceleration.
* 3.55: Similar to 3.50, a compromise option.
* 4.10: Offered better acceleration and towing capacity but reduced fuel economy.
To find the *actual* gear ratio of a specific 1989 Ford F-150, you need to check one of the following:
* The Vehicle's Build Sheet (if available): This document lists the options, including the rear axle ratio.
* The Driver's Side Door Jamb Sticker (often called the "VIN sticker"): Sometimes, but not always, the axle ratio will be listed here.
* The Differential Housing Tag: Located on the differential housing itself. It should have a code that will indicate the gear ratio (you may need a Ford parts catalog or online resource to decipher the code).
* Manually Calculate It: Jack up one rear wheel, mark a spot on the driveshaft and the tire, rotate the driveshaft one full turn, and count the number of rotations of the tire. This will give you the ratio. (Be extremely careful doing this!)
Without checking one of these sources, it's impossible to say definitively what the gear ratio is.
