2002 Ranger 4.0L 4x4 Automatic Tranny/transfer case issue

[Grumpy_old_man]

I made a mistake(?) on changing my automatic tranny fluid and transfer case fluid 2 weeks ago @290k and immediately afterward I have had issues. When you are in drive no issues until you are off power like descending a hill or just coasting up to a stop the tranny/transfer case makes a horrible sound like gears grinding, a touch on the gas stops it only briefly or untill you put power to it. so the temp fix for this is to one foot on the brake and one on the gas. Also the is an intermittent issue with reverse doing the same grinding noise the only cure for that that I have found is to put the transfer case in 4L and it works with no issues. I am at a loss on what to do, throwing additives at it did not work. Can any of the more intelligent folks on here point me in a direction

 

[franklin2]

What was the mistake?

 

[pjtoledo]

what fluid did you use?

and about "Grumpy_old_man".....
several of us already are fighting for the rights to that title

 

[Grumpy_old_man]

Mercon V in Tranny, Mercon LV in Transfer case
The mistake was changing it with the high miles, I was warned not to change it but you can't tell us older folks anything