How many hours to remove and replace a transmission on a 2004 gmc envoy 4.2L,4x

Hello, One guide places the job at 8.5 hours. However, you should have the issue diagnosed before replacing the transmission. It may not require a transmission rebuild or replacement. There are lots of 4l60e transmissions out there, and every transmission specialist has seen hundreds or thousands. They'll be able to diagnose it with ease.