Groan type noise while steering at low speed?
 

I've had this noise for awhile , but it appears to be getting a little louder. This is an '05 T&C with over 100K miles. Probably 2 years ago, I did have the power steering fluid changed at some oil change type place.

The truck is still steering fine, etc. but the noise is really annoying. It's muted and I can't really hear it if I have the radio going. It sounds to me like the power steering pump itself or the sound of two surfaces rubbing against each other as I turn. It starts/stops in step with moving the wheel. Any ideas? I'm just not sure what the problem is. It's hard to hear it outside the truck. Thanks!

anyone? just trying to get an idea of what might cause this noise when steering. thanks!