oil leak D6 9U

There normally is no crankshaft seal. Depends on bearing fit and screw thread feature to direct oil back to the sump.
There is however a rather involved retrofit seal system that Cat supplied later.

Hello Old Magnet ,

Is there more information from this retrofit seal ?
Or could the oil come from the oil cluch ?

Thank you , Gilbert

Here is the seal information....

A leak between the block and flywheel housing is more likely a gasket problem.
The crankshaft seal is primarily to prevent oil transfer from the engine to the oil clutch housing.

I had a bad oil leak like yours on my d6b. The pin that supports equliser spring craked the cross member, and the cross member sheared off two rear pan bolts. Had to rebuild the cross member and make a new pin.

The 8/9U doesn't have and equalizer spring pivot pin. Leaf spring is seated in its own cross member saddle.