Unidentified Noise

[dave.b]

I don't know how to describe it other than a kind of noise similar to a throwout bearing, but my car is an auto...any ideas anyone? Kind-of a muffled tututututut or in a comic book language "thbbbbbbttttt". It doesn't increase in frequency w/ speed or RMP, just kicks in at exactly 3k and quietens down through higher revs. It will not do it in neutral. Car runs great, but the noise drives me a little crazy. I will eventually take it to Toyota but I've been trying to avoid it.

Thanks in advance for any input.