2015 66rfe sounds like belt noise when downshifting

[brian08]

I have 2015 2500 6.4 sounds like belt squealing when on high way around 1500 rpm.. If I accelerate hard or tow haul it doesn't do it. The tranmission doesnt seem like it slipping.

 

[Audiowriter]

Could possibly be an idler or tensioner pulley on the serpentine belt track...???