What can make squealing noise from the front of my 91 Toyota 22re 4x4 truck

What is your question?

Lately I have squealing type noise that comes from the engine, no noise at idle or when rev the engine, but when I'm moving over 15 mph you can hear it. Put in neutral and moving still there, stopping or breaking doesn't matter. Moving noise, stopped no noise. I thought it was my brakes, but noise doesn't change when braking. I thought might be belts, but when you rev the motor no noise. I'm stumped.

What makes this problem better or worse?

When it wet or damp outside

How long has your 1991 Toyota Pickup had this problem?

Months