96 aurora ssqueeking sound from trans area

hey everyone , squeeky, scraping, chirping sound coming from transmission area. switch gears smoooth . had a flush, but didn't change filter. could that make the difference or could there be something else in that area making sound. it makes sound in park and neutral. if i put it in drive and keep foot on brake can't hear it. if start moving u can hear too. the spped of sound gets faster or slower as i move. please can anyone help me. the sound is on driver side under the hood. i read alot of post and guys give great help to each other.