My 2000 GMC Sierra truck is in great shape at 150,000+ miles with one exception. Road noise has become so loud that my wife and I have to practically shout to carry on a conversation at speeds above 40-45 MPH. Is there an after-market fix to improve the situation?

You probably have a rust hole somewhere. Either that or your muffler is bad. Check for both.

One of our regulars, “Mountainbike”, installed acoustic sound-absorbing mats inside the interior panels of his Scion tC a few months ago, and he stated that it is very effective. If he happens to read this thread, he can advise you about the brand of the material that he bought, and will likely have some installation tips for you.

However, if the noise level of your truck is higher than it used to be, I would suggest investigating a mechanical cause before you decide to make the noise less noticeable.

Some possible causes:

A dry or badly-worn differential (this needs to be checked right away!)
Worn tires (some tires become incredibly noisy after 10k or more miles of wear)
Wheel bearings that are badly worn (this also should be eliminated as a cause before you try to stifle the noise)

Bad wheel bearings are quite common in these trucks as they age, and will cause the condition you describe. They often sound like you are driving on rumble strips all the time. Get it checked out soon before they become bad enough to cause a loss of a wheel or other damage.

Definitely investigate possible sources of the sound as VDC suggested. You cannot and should not compensate for noise caused by worn out drivetrain components, worn tires, or especially a leak in the exhaust. Be sure evrything is in good shape as step one.

At the same time be aware that 11 year old pickups will typically have more road noise than new ones. Road noise (much of it actually drivetrain noise) comes from worn gears, synchros, U-joints, etc and from bushings. Busings are rubber and when new they isolate sounds from traveling into the cabin. But as they age, they become hard and cracked, and far more nose can propogate through the bushings and into the truck. Many mounts now are “hydraulic” (filled with fluid) and these can also crack and become void of that damping fluid. I think a good, thorough review of the bushings when you’re evaluating the undercarriage for cause is in order. Don;t forget the critical body mounts and bed mounts.

Once all of this has been addressed, then you can begin to consider sound damping. It does make a difference, but it won’t compensate for the other problems.

I agree with shadow fox assessment if the noise has been developing. This is about the right time for PU trucks to start rusting throughout the cab…especially around the doors, sills, rear quarters and under the floor mats.

While this is no substitute for worn parts or rust holes the self adhesive sound absorbing mats are from 3M and possibly Dynamat

Just curious but could you describe the noise? Humming, roaring, howling, whining, or what? Front, rear, or both?

I’m in agreement with others you need to have this looked at to determine the cause rather than try to stifle it. If it’s a rear end fixing to come apart an axle shaft with wheel attached sailing off into the roadside ditch at 70 MPH is not something you want to contend with.

Reminds me of the old Midas commercial: “Ya muffler! Fix it!”

New noises need to be fixed, not covered up, as folks have said. You may be surprised at how quiet your truck can be.