The big hoses go to rad and somewhere up top, the oil leaks out of the joint between the two parts. There doesn't seem to be a gasket, you would think that if it was going to leak it would be water leaking outas its so near the radiator hose.
I think I will just chance it and try to repair it on Sat morning, make a gasket or maybe replace an o ring, I can't find any reference to it in my manual or on the net.
I'll post some pics if your interested

Andy

 

If those larger hoses go to the radiator, then this is some kind of external cooler for the engine oil, but what is baffling me is why they would still have both sets of oil lines down there... Almost is like they kept the stock oil cooler in the hot side tank of the radiator, but added on this additional cooler that has engine coolant running through it... Odd and very complex. I would have thought that an air to oil cooler would have been more economical, but who knows what weird laws/directives are at work over in Europe... My advice would be to maybe try to get an exploded view of that component from a local Chevy dealership... See if they can help. Go in and explain that you need the gasket for the end plate on the auxilliary oil cooler under the radiator.