Crackling sound at low speed

Ok, here is another one. This truly worries me! I have a 1996 Explorer XLT 5.0L AWD. At low speeds (1-10 mph) I can hear this very loud crackling sound. I only hear it at these speeds, usually when I'm going through a fast food drive-through, or when I begin to accelerate from a dead stop at a traffic signal. Any ideas out there? Has anyone dealt with this before? Again, it's only heard at low speeds, and when the SUV is in motion. Sound appears to be coming from the area behind the front tires, more so on the driver's side. Thanks!

where does this sound seem like its coming from, (rear end, engine, underneath)?

Most likely its wheel bearing they make similar noices like that when they get bad

where does this sound seem like its coming from, (rear end, engine, underneath)?

Thanks for the reply sickrick111. The wheel bearing is definitely a possible source of the problem. The noise is coming from underneath the driver's side of the truck, behind the wheel to be more precise. I guess I'll need to take it to a mechanic and have it checked out. In regards to your other posting, have you had trouble like this or knew someone who did? The noise is just so weird, it sounds like brand new rubber wheels be driven over a newly polished floor. Strange. Thanks again!