Unless it has a steel stator the converter failure would most likely be aluminum pieces. When mine killed a steel stator this summer there was WAY more magnetic particles then yours. the metal actually stuck the rooster comb detent ball. Couldn't manually move the shifter. The only thing it hurt in the trans was light pump gear damage. Gears got replaced. I agree with others this is a rear clutch issue. If it's got a cloth filter not much metal can make it into the internal valve body area.
Doug