Hi all! I have an '03 DD 4.7L. I just recently had the front wheel bearings and new front brakes put on. I thought that might be the issue with this noise. For example, when I'm stopped, and I accelerate somewhat quickly, I get a scratchy-type scrape-y noise coming from underneath. I thought the forementioned repairs would fix it, but no. I can't tell off-hand if it's a u-joint issue, tranny issue, or what. I know it's not the front wheels, because I can hold the brake, and spin the back tires and hear the noise still.
Another part, which may or may not be related, is that when I get up to about between 45-55 mph, i get like a low rumbling sound like I'm going over tiny rumble strips. seems to go away momentarily when I give it gas, but comes back when it gets back into the speed ranges i spoke of. I'm not sure if the issues might be related, or perhaps a leak in the exhaust somewhere. I'm not totally sure, at the moment.
If anyone has any insight on what I could look for, I'd greatly appreciate it. Thanks in advance, either way.

 

I'd start with the u-joints, they're probably the easiest and cheapest thing to check/replace. Beyond that you could check to make sure none of the weights came off of the driveshaft, then bearings and so on.

 

Thanks, guy. I will def. be looking at that today. It doesn't do it on "soft" acceleration. Just when I give it a little punch "from the line".

 

sounds like what i had. was the fan clutch. easy to check.

 

The easiest way to rule that out would be to see if it still made the noise if you hit the gas in neutral.