Weird Noise at certain speeds
 

Just shaking down my recently purchased 1998 Suburban K1500. When driving down the road, no strange noises. As soon as I get to 42 MPH, a medium pitched hum starts up. This lasts until the speed reaches about 52 MPH and then it goes away (or at least I can't hear it). It's fairly loud.

The noise doesn't seem to change with different gear selections; (OD/3/2) all sound the same. If I let off the gas, you don't hear it either so could it be the fuel pump? The noise sounds like it's up front.

Any ideas what to check?

Weird or what?

Thanks
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Does it change under load or when coasting?