I had wondered about the fan clutch ...
Really sitting here at work and wife driving the truck, not sure if it is mechanical or electric, but I THINK it was belt driven.
When cold my 1998 really made some noise.
But it was a whirring LOTS of air moving sound and easy to identify.
Few minutes of running even in zero temps and a couple throttle revs usually freed that one up. I will look into though and post what if anything I find, Thank you!!!