[77newell]

My DD manual shows what Jon mentioned above - external supply line connected to the top and another line for oil drain connected to the bottom of the center housing. It is more likely that the supply line is leaking than the drain line, especially if the supply line connects to the center housing via a flat plate held in place by two bolts. There is a gasket between the plate and the housing. Given that DD has updated that connection to an all pipe threaded connection (the first version has the pipe threaded reducer screwing into the plate) that eliminates the plate and gasket. If your turbo has not been updated to eliminate the plate I wouldn't be surprised to find that is the source of the leak. DD can tell you whether you need to replace the turbo or if the existing turbo has the threaded connection in addition to the bolt holes for the plate.