This bulletin involves inspecting the rear axle on 2018-2019 Ram 1500 trucks built on or after April 3, 2018, and on or before Aug. 8, 2018, for proper fluid level.  

Applications include those trucks equipped with conventional differential rear axle with 3.21 gear ratio, 3.55 and 3.92 ratios, and anti-spin differential rear axles with ratios of 3.21, 3.55 and 3.92.

The customer may experience a growling noise from the rear axle. Raise and support the truck. Inspect the rear axle fluid as follows:

• Clean the area around the fill plug and remove the fill plug.

• Take a piece of wire or zip tie and make a 90-degree bend, 2-inches from the end of the wire. Make a line at 6mm (.250-inch) from the wire tip for a lubricant level indicator line.

• Insert the wire perpendicular to the fill plug hole and use it like a dipstick. Check the fill level from the bottom of the fill hole.

• Remove the wire and verify that the fluid level is within the marked line from the 90-degree wire bend.

If the fill level is within spec, reinstall the fill plug. If the fluid level is not within the spec, the rear axle assembly may need to be replaced. Replacement rear axle assemblies are pre-filled with fluid.