Cummins V504C leaks a lot of oil from front end at high RPM

I have an old Grove RT60S crane with a Cummins V8 engine V504C.

Unfortunately, at high RPM (set with throttle) the engine starts leaking copious amount of oil somewhere from the transmission side.

Now sure what causes the leak, we power washed the top and it is not from the top, and it is hard to see on the bottom.

Any ideas what it might be?

Thanks

Cummins V504C leaks a lot of oil from front end at high RPM