I am assuming you have the V6 engine.
It does need to be at TDC of the compression stroke. You can make sure it is the compression stroke by watching the exhaust cam close and the intake open as the piston travels down. This would be the intake stroke. When it travels up, both cams willl be farthest away from opening either valve and the piston will be moving upward. This is the compression stroke and the crank pulley has a mark on it for TDC of the number one piston. You just want to make sure it is the compression, or at TDC it will be firing, when you align the crank mark and the cams.
Then turn the crank around 6 times to see if everything still lines up after rotation. Sometimes you can be off a tooth and rotating it is a good idea to ensure proper alignment.
May, 14, 2012 AT 10:45 PM
Put engine no.1 piston on its compression stroke/TDC and align cam and crank to its markings as indicated in the repair manual