On the 3.1 - piece of cake. One caveat - have you ever done this before? If not - buy a repair manual from a parts store that has step by step instructions. The main thing to keep in mind is to clean off the old gasket as thoroughly as possible. Leaving even a little of the old gasket on the manifold will make for a bad seal and your new pump will leak. It's not necessary to use anything other than the gasket that comes with the new pump IF you clean it completely prior to installing. Us a 'light' putty knife to evenly take it all down to the metal - be careful, however, as the block is aluminum - too aggressive with the removal and you could damage the area.
Good luck
