OK, so I bought a new timing chain set and tensioner to try and get rid of the tapping int he Jeep (heard this could be a source, and besides, it's never been changed and the Jeep has 130K miles on it, so I figured it would be good to change anyway!), but acorinding to the FSM, you need to remove the oil pan to do change it. 
I was wondering if this is really necessary or not...  Anyone has done this before?  This is my firt time, so I also want to get an idea of how long it will take...