Obligatory 'Strange Noise' Topic, Caliper's Locked Up? Options

[senick]

Well, I have a 95 AT200 w/AT. Lately (for the past month) I've been hearing a noise from underneath. It's on and off, and mostly there's no noise. But when it happens, it's at low speeds, and it sounds like metal on metal contact, like the brakes are rubbing (which is what it could be). My theory is that it might be the exhaust, as I've already had some ghetto welding done on it, but I think the cat's breaking from the inside out, and the metal shavings burning on the inside are what's making the noise, which would explain the intermittent nature of the noise and why I usually only hear it at low speed. Does that sound reasonable?
As far as symptoms, she's driving like a top, aside from some rough idling at times. Shifts are great, no misfiring, oil and trans fluid are fine, engine temp good. I just had the passenger side CV axle replaced, and I know the sound isn't coming from the driver's side.
I know this is a pretty poor explanation of the problem, but if it happens again I'll try to record it and then you guys can hear it. But meantime, do you think it could be the exhaust?

Edit: The noise seems to amplify when I hit a sharp incline, or roll through a low spot in a parking lot, so that the front of the car is higher than the back.

This post has been edited by senick: Oct 6, 2011 - 10:10 AM

[rave2n]

Could be the cat...

Could also be the hub bearing. I'd check both.