4l80 engages but wont move

[Lettinn]

Hi.

Really need comments on this one. Have 1998 GMC SIERRA 1500 6.5 diesel with the 4l80e trans.

 

When i put it in drive or reverse it sure engages and the truck moves as normal but as I rev the engine it wont move.

 

Fluid is not burned and no metal debris in the pan, so I figured it might be the converter and replaced it with new one. No luck there at all.

 

So if anyone with any knowledge in those trannys has any ideas wats wrong with it please step in and give me your comment.

 

Thanks in advance.

Kris.

[silveradosid]

if it is 4x4 check transfer case