Curing shift CLUNK in 2005 Tahoe

[Spartus]

My 2005 tahoe has that dreaded CLUNK every time it shifts. I've read that some people have cured it with a custom transmission tune. Does anyone know what changes I need to make in order to help this situation?

I've thought that maybe the "Desired Shift time Vs Torque" tables could help this, but am not sure. I changed all values down to .200, and increased line pressures by 10% and the clunk got worse. So maybe I need to lower shift pressures instead?

Thanks for any input.

[EC_Tune]

GM tried to fix this on the 05 vehicles and ended up making the trans a bit weaker in the process. The Clunk is just something that you have to live with with a 4L60E.

[Spartus]

The clunk appears to come from the Driveshaft to Transfer case slip yoke. When shifting from D to R, R to D, D to R, there is an obvious LOUD clunk. It appears that there is too much slop in the splines. When driving, the 2-3 shift sounds more like a hammer slap onto the frame of the Tahoe. Not the typical clunk I'd think GM would find to be normal.

Maybe I'll try lowering the 2-3 shift pressure instead of raising it.

[seven ends]

I had a loud clunk and pulled the rear drive shaft and packed the splines with "a lot" of synthetic wheel bearing grease. Still not perfect but a huge difference in the right direction.

[low_lq4]

I replaced my U joints and everything was back to normal.