Have a look at the coolant block off plate just behind the engine (on the adapter) on the passenger side. If yours is leaking, read the links below. I was able to change it without pulling the engine/trans. It's tight, but I was able to get my paws up there to work the two bolts.
http://www.dieselplace.com/forum/sho...6774&highlight=
http://www.dieselplace.com/forum/sho...1562&highlight=
Jon
04 Silverado 2500 HD Duramax (LB7) 173K Miles
97 Passat TDI 200K+ Miles
00 Passat 1.8 150K+ Miles
97 Corvette 110K+ Miles