I just received word that the ex-CN "slug" is ready for testing at NB Southern's Dever Road shops. They are called "mother-daughter" units. The mother unit is 2318 and the ex-CN unit is numbered 008. They should be tested in the yard on the weekend, and once the bugs are worked out, they will be tried on the mainline with a test train next week.
The slug has been around for a while. I saw it back in May 2008.