funny shift from 2 to 3rd

[sawtooth1]

In the morning when i get in my truck i leave the driveway and the 1 to 2nd shift is perfect then 2-3 it feels like its trying to start to shift then after half a second goes into gear with a slight clunk. You hear the clunk more than you feel it though. As you drive the truck this issues almost completely goes away but you can still barely tell something is a little different from changing 2nd to 3rd gear. My truck has always done this some just seems a little worse now. If i go back to stock it still has this issue. Anyone else seen this issue or know how to fix it?

[BIGBILL105 45]

Sounds like your torque converter may be going bad. That's what mine was doing while it was shreading my tranny. But may be different since you got a 6.4

[ZeroOne]

Shifts will be different on a cold transmission. On mine, almost more abrupt until it warms up a little. Also, and I don't remember the details, but the 2-3 shift is different than 1-2. Something to do with it being a more complicated action within the transmission. Have you checked your fluid levels recently? Levels that are slightly off can cause odd shifting.