When you've got the valve body down; that's a good opportunity to take a screwdriver and pry between the lugs on the sun gear shell and front (direct) drum. Then pry from the front of the direct drum; pushing it back; to determine end play. If those particles came from a thrust washer and your end play is 1/8" or greater, take the trans out and drop out the front drums at least. The direct drum is the one the front band rides on.
