What is the rear end gear ratio of a 4.2 liter F150?

The rear end gear ratio of a 4.2L F-150 depends on the model year and the specific options chosen when it was ordered. Ford offered several different gear ratios across the years this engine was available. There's no single answer.

To find the gear ratio for *your* specific truck, you need to:

* Check the sticker on the driver's side doorjamb: This sticker often lists the axle ratio. Look for something like "axle ratio: 3.55" or a similar notation.

* Check your owner's manual: The owner's manual should specify the axle ratio.

* Look at the build sheet (if available): If you have access to the original build sheet for the truck, it will clearly state the rear axle ratio.

* Look at the casting number on the differential: This is the most accurate but requires physically inspecting the differential. The casting number can be cross-referenced online to determine the gear ratio.

Without more information about the specific year and trim level of your 4.2L F-150, it's impossible to provide the correct rear end gear ratio.