I had all sorts of fun changing out the casting plug in the rear of the drivers side head....
Some said they cut a hole in the firewall but I was NOT going to do that.
Ended up using a battery powered ratchet to put a large self tapping screw in the casting plug. Put some vice grips on the screw then used a small pry bar to pop it out. Was able to use a small sledge hammer to tap tap tap tap it back in.
2004 Jeep Liberty
1998 Jeep ZJ 5.9
1994 Jeep ZJ I6
1989 Jeep Grand Wagoneer 360