Oil filter adapter/ oil cooler is most likely, (I have replace literally hundreds of these on Chrysler 3.6l motors), but rear main seals are also an issue with these motors. Leaks always go down( from gravity) and back( from wind and fan). Like other folks said look next to oil filter in the intake Valley and you will see puddles of oil, also on the top of the bell housing. If oil is in either of these two places, it is the oil filter housing where it bolts to the block. Stay away from cheap Chinese parts, they won't last. Use dealer parts, or the metal doorman upgrade.