The oil patch is where the exhaust manifolds meet, the 3 towards the operator and the 3 towards the fan end of the motor, it looks like there is a coupling linking the 2 together. That 6620 you have sounds nice, but like The Red said to your post, I think you're wanting a little too much, considering the market is now getting flooded with 9000 seriers machines. Do you also have a 7700 for saleIJ