What I have a 2011 Silverado 1500 with a 4.8 and 4l70. I know I can put a 6.2 in there and change ecm parameters no problem. Question is what kind of segment swap or TCM changes would need to be made for a 4L80? I am looking into weather or not the push button T-case will swap from a 4l70 to 4l80. Maybe someone here has done this and can help me avoid pitfalls.
You can keep the same 4L70 Segment and do the relay method to control the trans, works good, 4l80e has a 32 spline output shaft vs 27 on the 4l60, you will need to find a transfercase with 32 spline input shaft, or swap the input shaft of your current transfercase.