2012 Yukon noise when accelerating and after shift

[Roundyround]

2012 GMC Yukon SLT 4x4 with 6L80 MYC transmission and NPO transfer case, with 185,000 miles. Yukon drove fine until a cold snap then didn't want to move over 50 feet at a time. Changed fluid and filter, no chunkies in pan, but there was brown goo that looked like clutch lining material. Cleaned the pan and reassembled with new fluid, seems to drive fine, but there is a weird squeal now when shifting during acceleration that wasn't there before. The noise is heard a few seconds before the video ends. Any suggestions on where to go from here?

 

[Roundyround]

https://drive.google.com/file/d/1nS6pp9KcMSwK8nefcTW_hiObTamBG9Rh/view?usp=sharing

 

[Doubeleive]

2012 GMC Yukon SLT 4x4 with 6L80 MYC transmission and NPO transfer case, with 185,000 miles. Yukon drove fine until a cold snap then didn't want to move over 50 feet at a time. Changed fluid and filter, no chunkies in pan, but there was brown goo that looked like clutch lining material. Cleaned the pan and reassembled with new fluid, seems to drive fine, but there is a weird squeal now when shifting during acceleration that wasn't there before. The noise is heard a few seconds before the video ends. Any suggestions on where to go from here?

no video and squeal is usually a belt slipping.
easiest to just upload video to youtube and then post a link here.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I can't tell by that short noise at the end of your video.

@NickTransmissions is our resident transmission expert, and he will chime in with his thoughts and perspectives.