Already plugged in the OBD2.... P0894 I believe said said component in transmission slipping. Which is very generic and could be a number of things I'm replacing the trans and transfer speed sensors today.
After fully warmed and trans at about 150 or 160 it shifts hard into 2nd am 3rd anyone experience this it's a 2004 2500 4x4 suburban w 8.1L and 145k miles