just wanted to add my .02
ive personally removed the oil pan and done the gasket. the headers don't need to come off,
also PB Blaster is the way to go.. its some of the best stuff ever made, really helps alot.
Air tools make the job soooo much easier, but it can be done with some PB, breaker bar, and paitence... be careful in removing the bolts sometimes they can rust heavily, and bind.
When removing them by hand with a breaker bar, you increase the risk of snapping a bolt off. Air tools will lower this risk due to how the torque is applied. By hand its constant torque, air tools use repetitative torque and bump it in tiny incriments very quickly. The constant torque of the breaker bar, starts to stress the bolt, and continues to fatigue the bolt as you continue that stroke.
Also, when removing and reinstalling make sure to follow the manual, there is a certain order to removing and installing the bolts.
HTH
Mike