Distinct noise at highway speeds

I have a 2003 Nissan xterra se with 93,0000 mi. When i reach speeds greater than 60 mph it makes this rapid somewhat clicking noise. the dealer suggest to replace the belts. Of course that did not resolved the issue. then they claimed it was coming from the exhaust so they tinkered with it. it was gone for awhile but now it has return. any suggestions?

Thank you very much…

When I hear that a system was worked with and this eliminated the sympton for a short while, am I to conclude that they “worked with” the correct system but the work quickly failed? How do others view the comment “it worked for a while but then the sympton returned”? If they had not identified the correct system making the noise then the sympton would not have gone away, even for a little while.Are we to continue working with the exhaust? Or do we have a case of customer “placebo” effect?

I generally intrepret comments like this as an indication that the mechanic corrected the symptom but not the cause. I’m generally curious as to exactly what was found and what was done. The OP rarely has that level of detail.

In this case I’m wondering if there’s something like a loose heat shield and it was secured, but not well.

Someone needs to get under the car.