2001 Olds Alero 2.4 lit 4 cyl - oil leak

Hello,
I am having a mysterious oil leak from engine.
I see droplets on the driveway.
It is from the back side of the engine close to the firewall. It is not from power steering pump or the oil pan gasket.
I am unable to trace it.
Please help if you can suggest any where I can look.
Thanks
Jay