Transmission Thunk

[cekkk]

2014 Denali XL with 70k miles has begun to make an occasional sound when coming to a stop or down shifting as when making a 90 degree turn. I haven't check transmission fluid yet, but I had an oil change in August at a high-end, I would call it, auto shop. Less than 2000 miles since. They check everything. Any thoughts?

 

[Big Mama]

Where does the noise come from? Could be lots of things but yes start with fluid and smell for burnt fluid