The DK-19 and DK-22 just arrived. It does appear that a threaded lock ring is needed to attach the two.
Tomorrow is Saturday, and so I'll go up to the big camera store where I bought most of my gear and will ask them how to resolve this. They've got boxes and boxes of little Nikon bit & pieces, and usually give me what I need for no charge.
But, what we both need most is information. These guys are real Nikon old-timers. I'll get back to you in 24 hours. All is not lost!