Weird rattling noise, Anybody? Any help? Options

[richee3]

So... My car makes this funky-sounding rattling noise. I thought at first maybe it was something in the body or something, but I know it's not now. It only happens specifically at 2,000 RPM, all 5 gears or even in neutral when I'm just revving it up. There is nothing loose, I've checked everything. Maybe something in the transmission? One of my friends who does a lot of work with Nissans (has an RB20DET in his 240SX) thinks it might be my clutch. He said it sounds like it's broken, like it's missing a chunk or two somewhere. Also, I don't know if this is related, but every once in a while my car does this weird thing where it acts like the clutch is too hot and is slipping. Like when I take off in first, it shakes really bad and I have to give it more gas. It'll do that for a couple of days then it will be fine again. So I know I need to replace my clutch anyway, but what is making that rattling noise? I figure while I'm taking stuff apart I might as well get that fixed too.