For 1990-2009 cars

Cause | Correction
--- | ---
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.