Fairly new to the forum and have a 6L80e in a LC9 swaped Land Rover Defender. Ran a search and didn't find anything similar to my concern so really would be pleased to get some sort of feedback on it!
All of it was removed from a 2012 Chevy Silverado with 54K miles.
I have a VERY annoying issue with a high pitched whine in all gears (loudest about 50MPH) pitch seems to increase with speed. Doesn't change at all with gear changes. Location wise the sound is coming from transmssion. Could be the t-box - but this was a new unit from ash croft in the UK.
An annoying downshfit clunk in lower gears. Also same from reverse to drive.
Videos - link to YouTube is attached to help. Put sound on and you can hear it. Happy to provide more info - I just purhcased a HP tuner but have yet to play with it.