AT shift noise

[waterlogged]

I have a 1997 K1500 Sierra, and have noticed a clunking sound coming from the drivetrain under normal driving conditions. It usually happens while shifting from 1st gear into 2nd. It doesnt seem to be effecting driveability now, but i would like to find out what it is in case this could solve a problem down the road. Any suggestions what might cause this? I do have a TB spacer and have heard that it may be the problem, but I would like to get more input.

[GMSea97]

have you checked your u-joints lately...Once they become worn they may make a clunking sound when pressure is released and then reapplied. You can check this by going under your truck and try turning the driveshaft with your hands, you shouldnt have much play in it...

 

thats my two cents and I figured it would be a easy thing to check just incase.