ok so here it is. I have a 2011 Silverado with a 5.3 6l80. it had a 4.3 4l60 original in it. I have been running the 5.3 6l80 for over 3 years no problems. it has a laundry list of mods and up grades done to it and its N/A. 3 weeks ago the 6l80 went out on me so I took it out and found out the techm is officially bad as well as the gear rings. some of the rings in 4th gear are fused together and cant be separated. so I went and bought a verified 10,687 mile 6l80 and installed it. I drove the truck to the dealer shifting threw all 6 gears and verifying it works as it should. the dealer took it back to do the dealer flash. they told me that at the end of the flash it would kick them out and not finish the flash. no I drove it 10 miles home in first gear and hooked up hp tuners to it. in scan mode it gives me the U0101 code but in write mode it doesn't even see the tcm to do any thing with it. I'm puzzled now as to what to do with it.