there is a gasket where the drain tube meets the turbo center cartridge. that can be bad or the 2 10mm bolts that secure it can be loose. if it looks like its coming from the area where it goes into the block check the 2 hose clamps that connect the tube to the boss on the block, one may have loosened over the miles.
Good Luck.
Jim
Yes its a press fit. maybe you have a corrosion issue going on? Maybe pull the tube out of the block, rtv it and tap it back in. kinda tough with no real estate to work with but it can be done. check out to make sure it isnt dripping down from anywhere first though.
WPeschel, this is off the subject, but I was curious what you decided to do about your 175 HP P7100 pump. I'm hoping everything works out for you to get 400 HP.
Dave