GM P/N 12378514 Hypoid Gear Oil has ultraviolet dye already included within the oil.

Drain and fill the unit with new oil before using the J 28428-E black light, when inspecting for leaks. Ultraviolet dye J 28431-6 is not approved for use.

Restricted or damaged ventilation tube assembly

Replace the ventilation tube as required.

Worn, scored, or missing drain and/or fill plug sealing washers

Install new sealing washers and tighten the plugs per specifications.

Worn or damaged drive pinion oil seal

1. Inspect the torque tube propeller shaft oil seal surface for excessive wear or damage.
2. Inspect the torque tube propeller shaft bearings for wear or damage. A worn bearing may allow excessive movement of the propeller shaft within the torque tube.
3. Replace the components as required.

Cut or damaged drive pinion housing O-ring seal

Replace the O-ring seal as required.

Worn or damaged axle shaft oil seals

Replace the axle shaft oil seals as required.

Cut or damaged clutch pump check valve O-ring seals

Replace the O-ring seals as required.

Leaking clutch pump check valve

Replace the clutch pump check valve assembly.

Carrier housing porosity or a leaking side cover seal surface

Replace the differential assembly.