Shift Problem

[Sierra 2011]

What is going on with the transmission when the engine goes from 4 to 8 mode. ( or 8 to 4 mode) It bangs the tranny hard. This occurs in low rpm and 6th gear. GMC couldn't fix it. Any ideas?

 

[rarnoldsb]

Don't take NO for an answer. I have a 2011 Sierra and it doesn't do it.
8-4 is how many cylinders are firing.

 

[PGDriver]

Mine shifts smooth, I'd go back and ask to take one off the lot and see how it shifts....