It is possible for them to leak from where it mates to the block if the gasket/ seal is damaged. The replacement seal is $2.00.The part number is J3181288 that a Mopar part number. Im pretty sure its the same gasket for all 4.0 engines, regardless If its a OPDA or a distributor. If you are unfamiliar with the OPDA, what it does and how to properly remove it, you need to do a little reading. If improperly re installed the timing will be off and the jeep will not run, or run poorly. Its not a hard job its just a little tedious.