Not quite a squeal....not quite metallic

Hi. I have an annoying noise with my 1996 Ford Bronco 5.8L. It happens on start up specifically when it’s cold. It doesn’t have to be particularly cold, like 50F would cause it, but it gets worse as it gets colder.

It’s an intermittent noise, not quite a squeal and not quite a metallic sound. Each sound only lasts a second or so, but happens very frequently (like every few seconds) right after start up and slowly goes away after it warms up some. If I shut the truck off after its warmed up and then restart, the sound is gone. So it’s only while it’s cold.

I’m writing now because now that it’s getting colder it has started happening again. Any clue what it may be? Thanks!