The 3.3L has a Chain, the 3.5L has a belt that is due for replacment at around 105K miles. I suggest replacing the tensioner and water pump while your in there. There is no need to replace the hyrdalic pistion that keeps the pressure on the tensioner, but just the pulley itself. It will go bad on you. I had a 95' Concorde that made it to 117K before i had a problem with the belt, and it was in fact the pulley that failed. Here what i found:
I bought a replacement tensioner pulley, water pump and the belt itself. Cost was ~$200. I spent about 10 hours in the driveway working on it, but if i had to do it again, i'm sure i could do it in half that time. You will need a 3 jaw puller to remove the crankshaft pulley - your local auto parts store will probably loan one to you - Other than that, a simple rachet set should do the job...