The crankshaft rear oil seal is leaking.

Refer to Crankshaft Rear Oil Seal Replacement in Engine Mechanical.

The torque converter oil pump lip seal is leaking.

Replace the oil pump seal.

The cranked weld in the torque converter assembly is leaking.

Repair or replace the converter assembly.

Refer to applicable Allison Transmission Service Manual.

The oil pump seal ring is leaking.

Replace the oil pump seal ring.