tarpon4me

I'm at a loss and I hope someone can help. I have a mild grinding noise up front that gradually gets louder with speed. Sounds like worn brake pads almost. Throttle, coasting, doesn't matter, it's speed specific. All the U joints seem solid, hubs solid. Fluid in diff is good and clean. But, when I lock it in 4H, it goes away. 2014 JK Manual transmission.