Growling noise

I don't know how else to describe the noise, so I have to say that it sounds like a growl. It comes from either right in front of or below me and happens when I'm either pushing the clutch in or just releasing it to get the car going. So just as it is engaging. I don't hear it otherwise. You guys have any idea what it may be. I figure something in the drivetrain but I don't know what. Any help would be greatly appreciated.
- Justin

You guys crack me up. I knew I would get some crap like that. Really though, my drivetrain only has about 8,000 miles on it. I upgraded everything. I did a TKO500, Mcleod Clutch, Adjustable Quadrant w/ firewall adjuster, aluminum driveshaft, and rear end. Everything else was new from the fork, TOB, to the Retainer. Probably some other stuff too, but I can't think straight right now And I don't notice it all the time. It's only every once in a while. I haven't paid close enough attention but I think it happens when I hold the clutch in for a while or idle with it in neutral for a while. Thanks for the ideas, you could be right but it just seems soon to have that with all the new heavy duty stuff.