Been chasing a weird clunk at take off. Have checked brakes for hanging up, U-joints and everything else I can think other than greasing the output shaft and slip yoke (I think there was a tsb on it somewhere). Today I got both the tires off the ground and took a look at the amount of play in the rear differential. If you watch closely, you can see how much movement the tire I am moving has after the driveline has stopped moving and also after the other tire has stopped rotating. Seems a bit much if you ask me but I know nothing about what is going on in there. Also, that sound you hear when I'm moving the tires seems similar to what I am hearing at take off. Time for a rebuild?

9.75" with LS 3:73

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I would've guessed the yoke. The reason why I doubt it would be play in the differential because the torque converter would keep the back half of the drivetrain loaded, so there wouldn't be any slop to make clunking noises.

Maybe suspension?

 

Looks normal to me.