wierd noise 91 GT

when i am going about 0-20 mph i can hear a sound coming from the left front tire... i think... maybe cause i'm on the left side? but the speedometer sort of doesn't show an exact mph reading at that speed it goes up and down until i going faster than 20. the sound almost goes in rhythm with needle bouncing. i just wondering if anyone might know what is causing the sound

The speedo runs off of a gear in the trans, i doubt it is related to your speedo, how much mileage is on the car and do you hear the noise at other speeds as well?

These speedos are notorious for going crazy... it is very possible that the sound is coming from the speedo cable or the speedo itself. When the needle bounces like that it is common to hear a rattling sound... usually happens at higher speeds though... maybe 40+.
Disconnect your speedo cable from the transmission and see if the noice continues...

mileage about 140,000 miles and the sound gets quieter as i accelerate