Hi. I've been plagued with a mysterious sound coming from my Ranger that I just can't identify. It sounds similar to what a metal wire scratching on metal or glass might sound like. It's not piercing but it's not low or dull either. It never lasts more than a second or two but it does come and go.

It's happened for only a few days now - less than a week, I believe. For the first few days, it would happen most of the time when I turned a corner. Now, it even happens driving straight. It happens at any speed under roughly 40. If it happens over 40, I can't hear it from the other road noises.

I've tried jumping in the bed, but that won't produce the sound. I can't tell if it's the bed itself (which already squeaks as some beds do - but that noise is definitely a squeak, as opposed to this new scratchign) or not. Could it be the tailpipe rubbing against something? Could it be the rear leaf springs or even the rear drum brakes? Could it be inside the rear diff. itself? (My rear is going bad, I already know this; the pinion seal is leaking and the whole rear will have to be rebuilt soon, but I can't imagine what exactly inside the rear could make such a loud scratching sound over the sounds of the exhaust and road noise.)

If it helps, the truck is a 2002 stepside. I would be indepted to anyone who's able help or offer suggestions. I've done a fair amount of searchign but have come up with nothing helpful. Thanks in advance.