where can i get a full kit with everything i need to upgrade my 4L60E to a built 4L65E. and how much does a kit like this usually cost. trying to find out if its would be cheaper to do it my self. i can get a GM 4L65E from work for $1400 but the guys in parts said GM won't take my 4L60E as a core so the price would go up to $1800.