My 99 4.6 auto. 2wd has developed a scraping/rattling sound that seems to be coming from the tranny. I does it mostly under medium load combined with light throttle. Also, it does it mostly when near the point of lugging the engine in any gear. For ex: going up a moderate hill in overdrive giving it just enough throttle tokeep going but not downshift. Seems to be a little worse when weather and/or the truck is cold. Any ideas? TC? It has just under 150K miles.

Thanks!

 

Loose radiator fan or water pump shaft?
Rattling heat shield over catalytic converter?
Catalytic converter insides breaking up?
Check them out too.

 

Have you changed the tranny fluid?