so on saturday morning we were getting on the highway to go to new orleans for the day a soon as i got on the highway and started accelerating i sounded like my serpintine belt broke so I pulled over and shut it off and checked it was good climbed all over the truck all was good so took it back home and it wouldn't down shift had to shift manuelly monday got home from work got in the yukon and took it to the tranny shopthey hooked it up to the computer and said it has no codes and soundsfine so i paid 50 bucks and left got 2 miles away and lost all gears forwardand reverse i have the 4l60e tranny