Ok so I got this sound out of the blue, it’s hard to explain kind of sounds like a circular saw but not as loud but th saw spinning sound or like a pump sucking air. At first I thought timing chain but can’t hear the sound near front of engine. It seems to be coming from near the oil pan area or transfer case area. I hear it with the windows down if I’m pressing gas lightly in gear or in park. I checked my trans fluid levels they are good I know the fluid needs to be changed it’s quite darkish purple looking when I changed the radiator last week. Now ive asked on a few of my Facebook groups one guy though maybe a spin bearing but there is now drivability issues not tapping or knocking or oil pump. Where is the oil pump location on our trucks?