wow just sudden death. I wonder what happened. I don't suppose an autopsy was done.

 

I have never opened up a trans after a fluid flush, so I have some reservations as to just how much good they do.
I can tell you there is always some sediment to be found in the pan after removal and if the filter is changed, the pan cleaned you are absolutely sure there should be no crap circulating around that wasn't removed once disturbed by a flush and hopefully not getting into close fitting valves in the valve body.

 

Sounds the the best approach is drop the pan, clean any sediment out, replace the filter and then top it off. thanks all for the insight.

 

170K is a long time on a filter/ fluid drop, if it's never been done before, That means your break-in fuild is still in there. With all those particles, contaminates and such circulating and worn-out additives. Forget 20000 miles. I'd flush sooner like 10000 miles. Should have a magnet on the pan that will be full of metal. My 15 Malibu has no such pan, filter or magnet so 20-25k will be changing time for her.