Chirping sound coming from rear, any thoughts?

I have an. ‘18 TRD sport with 19,000 miles. I’ve noticed a chirping sound coming from the rear left end when driving on bumpy roads or going over railroad tracks. I first noticed this at my 5,000 check-up only because the weather was warm enough to have my windows down. I took it into Toyota and they claimed that when they drove it around, they couldn’t hear it. They told me that when they checked underneath, everything looked good.

I have a Truxedo low pro tonneau cover on my bed, and the guy at Toyota told me that may be where the chirping is coming from. I checked my cover and made sure everything was tightened down.

I have to go back to the dealership this week to get a coolant hose replaced and wanted to bring up the chirping sound again. Does anyone else experience the same thing or have any thoughts to what may be causing this? Thanks!

 

Maybe you have a birdy under that tonneau.

 

Believe me, that’s the first thing I checked for