strange scary noise please help

[ssb541]

when i start the truck in the morning no noise but when i start it after it has been warmed up or even in the late afternoon (mid 70's) it does it but then it stops after i put a little load on it, if i just rev it up it gets louder, i cant really tell where it's coming from it's loudest right on top but is still loud under by the tranny there's no noise from the intake or exhaust. it's kind of a howling noise please help

[92f150300six]

Howling like a bad fan clutch ?

[ssb541]

no i dont think so i unplugged it and it still did it and it feels smooth