replace all o-rings on the rails removed - BTW you don't have to remove both rails to get to the odd numbered cylinders...just be careful to move all electrical connectors and vacuum hoses just in case. Hardest part is getting the rubber hose off the fuel rail line - if I were to do it again since it's just a normal rubber fuel hose is to cut the old hose off at both ends and install a new hose with new hose clamps...and I just cut the old hose clamp off and replaced it with a normal screw type