Just a bit of background - my 2005 3.7 KJ has been going through a lot of oil for quite a while. Approximately a year ago I replaced the oil pressure sender and the front main seal, because both were leaking. That, and upgrading to the 2006 PCV system reduced the amount of oil it goes through, but it's still a lot. I'd estimate it's about a quart per 300-400 miles. There's a lot of almost impossible to remove grime and old oil on (mainly) the bottom of the front diff (from those old leaks, I assumed), but I never saw any really wet spots there, and never noticed any drips. I thought the engine was simply burning all the oil it's going through. Today, while changing the front differential fluid, I noticed wet oil on the bottom of the front differential, and the part of the transmission crossmember directly behind the diff. It was definitely engine oil, not gear oil from the diff. I can't see where exactly it's coming from, but it covers pretty much the entire front diff, and from there gets blown back onto the trans crossmember. Everything up front is dry. I checked the valve covers, oil pressure sender, oil filter, front main seal - nothing leaking there. The inside of the inspection cover is dry (I did not take it off, but stuck some paper towels in there and they came out dry), and the plastic channel thingy that lead from the oil filter to the rear of the engine is dry as well. So I'm pretty sure the oil is not coming from the front of the engine. No wet spots on the oil pan either. Does it sound like this could be a rear main seal leak? I know those are not common on the 3.7, but at this point I have no clue what else it could be.