On my 98 6.5, My dealer was ready to tear down the engine because of an oil leak. I took a look at it and showed them the clamp on my Spherco IC (from J. Kennedy) was loose and probably needed tightening. That solve the problem. Oil gets into the intake on 6.5 engines because of the oil breather (or something like that) and I imagine that some oil also gets into the DM. Because the low point causes pooling any plumbing would leak if their is not a tight fit. Check your fittings and see if this won,t help. On the Spherco their was a drain plug that I used about once a month to get rid of the excess oil,(usually about a tablespoon).
02 Sierra, 2500 HD SLT<br />Edge with Allison