What diff. does a 1998 4x4 z71 Chevy Silverado 5.7 have?

The 1998 Chevy Silverado 1500 Z71 with the 5.7L Vortec engine likely has a differential geared for off-road use, though the exact ratio isn't specified by just the model year and trim. Z71 was Chevrolet's off-road package, and that often included a lower gear ratio in the differential than a standard 2WD or even a 4x4 Silverado without the Z71 package.

What this means: A lower gear ratio (like 4.10 or 4.56) will give you more torque at lower speeds, making it easier to climb hills and drive through mud or snow. A higher gear ratio (like 3.73) would be better for highway fuel economy.

To know the *exact* differential gear ratio, you need to:

* Check the door jamb sticker: This sticker often lists the axle ratio.

* Look at the differential tag: This is located on the differential housing itself. It will have a number that indicates the ratio (e.g., 4.10).

* Check your owner's manual: If you have it, it should specify the gear ratio for your specific truck.

Without looking at one of these sources, it's impossible to say for sure what differential ratio your specific 1998 Silverado Z71 5.7L has.