@Bruck I love the cheap aftermarket stems for cobs. A little drill & file work, and presto, even better smoking pipe.

My thoughts are from looking at the other pipes, the black one may be better off sitting in a box until you find a pipe one day that is broken and can salvage a stem to use on the black pipe.

If that black pipe ends up being a "keeper" then http://www.norwoodspiperepair.com/ would be a place to have a stem fitted. The last job they did for me was two stems for a pipe and it ran $67.46.