I personally pulled an engine from a car in the junk yard that had a good engine and transmission. Since all is good, then I trust that the torque converter should be no problem being from a junk yard and also good. It's extra work to pull it yourself at this particular junk yard, but you pay $200 per motor, and you know it's good and where it came from.
This particular car had 99K on the odometer and on carfax.