i have a 99 silverado 5.3 4x4 , had this truck for awhile now and the truck has not shifted good since i owned it meaning when i first got it the truck would not shift by itself out of 1st gear into 2nd , which i believe the 2nd gear was out but would shift fine through all the other gears with no slipping what so ever.i had a friend that works on trannys look at it and see if it could be just a selonoid and he said there was a nice amount of stuff in the tranny pan and didnt think it would help, when i went to get the truck from his shop the truck would not shift out of 1st gear regaurdless of what i did to try to get it to .. also had a check engine light on so i checked it and it was code p0753 .. could this be it or is the tranny shot???