Growl / roar from engine area......help!

[Rottiefan]

Need help determining a problem with my '96 with 5.0L V8. Makes a growling or roaring noise that peaks up around 60 mph. I had the idler pulleys and serpentine belt replaced approx. 10 months ago, so I doubt its an idler pulley. Don't suspect the water pump shaft bearings, there is no play in the shaft. I've never had this kind of problem with any engine before, doesn't sound like anything I've ever heard before. There doesn't appear to be any loss of performance, just noise/vibration that I can feel thru the floorboard now. Any ideas would be greatly appreciated.

 

[performancenut]

Might try putting it on a lift and carefully inspecting the exhaust system as an initial evaluation.