It appears to be a modified converter, by someone in the past. Look closely at the ring gear mounting to the body. From the factory the 12" converter used a narrow (about 1/2") ring gear, and the 11" converter used a wide(about 1") ring gear. The 1" ring gear was a one piece unit, not like the one that appears to be a two piece (welded) ring gear. All 340's ran an 11" converter from the factory.
The other thing that makes me think it is not a factory converter is the poor welding job were the two halves are welded, plus I've never seen a factory converter painted.
In any case, if you're going to use this converter, it needs some attention. From the photos, I'd say the hub needs to be replaced(badly scored), and who knows what else inside the unit.