This may seem elementary but I have a 1999 Lumina LTZ with 150k miles. I have had no problems and enjoy the vehicle. I keep up with the maintenance schedule in the owners manual. I can't find any mention of a timing belt or chain? Shouldn't I change it soon?

no don't worry about it. They are designed to last the life of the vehicle.

Thanks for your help! I just was not sure and did not want to make an expensive mistake...