Ok, rule number one of
club: You must always post year/engine/trans and any other pertinent info before asking a question.
Rule number two of
club: You must always post year/engine/trans and any other pertinent info before asking a question.
Rule number three of
club: When in doubt, follow rules one and two!
You will always get better advice when you share your basic info. Even if you have posted it a 100 times before, and have it in your profile. If you are a paid member you can put it in your signature, just another member benefit!
If you have a 4.0, the oil filter adapter, the oil pressure sender, the valve cover, the oil pan, and the rear main seal are common issues.
Don't rule out a faulty filter either, or the accidental double-seal situation, but that is usually a deluge!
As said by the other posters, the 4.0 rear main can be changed out without pulling anything the trans.
As the quick disconnects on the trans cooler lines often leak, as well as the lines themselves, be sure and give them a good going over. Can you tell by the smell of the fluid?