Dodge - SRT-10 :: 2005 - Grating / Grinding Sound When Accelerating

2005 Dodge SRT-10 Quad Cab.... There is a strange noise, or perhaps I should say noises that sound most of the time like a grating/grinding sound. Occasionally it has less of that mechanical sound, and more of..well, like blowing air over your tongue with a lot of saliva in the way (like a cat purring with a hairball in its mouth??). Anyway, the ONLY constant I have found is that it only happens when I am accelerating (but not every time I accelerate). Most often (again there have been exceptions) it happens between 1500 & 2500 RPMs...typically just before the transmission would be inclined to shift to a higher gear - if it does shift into the higher gear, the noise stops.

Also, the moment I take my foot off of the gas pedal, the sound stops. About a third of the time, I can feel a slight vibration via my feet when the noise is stronger sounding. On two occasions (this is over a period of approximately 1 year) The sound was extremely harsh, and the truck was shaking.When I took it in the first time they told me it was the catalytic converter, and replaced it. When that didn't fix the problem, they decided it must be the other catalytic converter (yes it has two). That didn't fix the problem either.Ordinarily, rather than simply have them replace half the parts in the truck I would wait until something completely failed, thus making the culprit obvious. However, I am moving soon... and I don't want to be driving half way across the country pulling a large trailer and have the drive shaft, or transmission, or whatever - fall out.