2011 Silverado Transmission Shudder

[Kevin A. Tinsley]

2011 Silverado 1500 LT. 5.3L 153K miles. Transmission started to shudder, Dealer recommended new transmission. First transmission was good for about 300 miles. Shudder came back. They replaced valve body, shudder gone for about 100 miles. Dealer installed another transmission and torque converter, and inspected transfer case. Good for about 300 miles. Shudder came back. Shudder is intermittent, different speeds at different times. The only thing consistent is shudder at highway speed of 75-77 mph, and if I shift down to 4th shudder goes away. Shudder present in 5th and 6th at highway speeds. Taking it back for a 3rd time seems to be a waste of time. The shudder is like drifting off the road and hitting rumble strips. Just not as intense. Odd that the transmission seems ok for a short period of time, then starts back up. Ideas?

[fondupot]

FYI. You posted in the Colorado/Canyon sub-forum.