Keep in mind that all these designations are made up after the fact by collectors, not by Conn.
First of all the "Chu" tenor is a very late New Wonder or very early Artist - curved high E, but bell keys on opposite sides. That's the horn chu was photographed with in the very famous portrait. I don't think anyone really knows whether that's the horn he really played all the time; it probably is, but he could well have borrowed a better-looking horn from a buddy for the picture, or he might have just bought the new one but all his playing and recording was on an older one; no one knows.
Secondly, collectors, not the Conn company, have decided to call the second series New Wonder the "Chu" because it superficially resembles the horn Chu was holding in his famous portrait.
Thirdly, the introduction of the later features occurred intermittently and it wasn't always a straight progression. I have seen horns with the basic late mechanism (you can tell the stack mechanism especially around the high F and bis key) but with bell keys on opposite sides. I have seen horns with fork Eb long after you'd think it was gone. I've seen horns with all kinds of variants of left hand tables. Engraving isn't a real good guide either.
Unless you measure the tube you can't say whether what you've got is acoustically a New Wonder or a 10M Artist. Since they're darn close anyway and both have that essential Conn character, I'd not worry about what some collectors have decided to call it 90 years after the fact.
