I get what sounds like a squeal at or just before the engine changes gears. Only noticeable when merging onto freeway or making a pass on the highway. Any thoughts?

 

My power steering makes a slight squeal sometimes, like when changing from R to D while wheel turned when moving vehicle.

I don't hear squeals while doing as you mention, but check the PS level, and if never done before, replace the PS fluid with fresh.

Also inspect the serp belt. Look for damage or what appears to be glazed over. Does it feel like the belt is tight or perhaps seems loose, like a weak tensioner?