The rear oil seal of the engine crankshaft is leaking.

Refer to Crankshaft Rear Oil Seal Replacement in 7.2L Diesel Engine or Crankshaft Rear Oil Seal Replacement in 7.4L Gasoline Engine..

The metal-cased, lip-type seal at the front of the input charging pump is leaking.

Replace the pump seal. Refer to Allison service manuals.

The seal around the outer diameter of the oil pump is leaking.

Replace the outer diameter pump seal. Refer to Allison service manuals.

The cranked weld in the torque converter assembly is leaking.

Repair or replace the converter assembly. Refer to Allison service manuals.

The torque converter pump hub at the seal area is worn.

Replace the torque converter pump hub. Refer to Allison service manuals.