I just bought a 2000 S10 ZR2 yesterday and when I test drove it, I didnt notice anything. But I noticed after I bought it that it makes a goaning sound from the front end sometimes. It isnt related to acceleration or the engine RPM. But it does do it more often when its above 50mph. If I move the wheel a little bit the sound goes away for a second. Please let me know if you've had this happen or you know what it could be. Thanks.

If the noise changes when you turn the wheel a little going down the road you have a bad front wheel bearing or bearings.
It was bad when you bought it even if you did not notice it then..
Take it back where you bought it and see if they will fix it on there dime.
Good luck
MT