Given the recent determination that the Pro1000 is just a 12" Pro200 and a ProTB24 is just a Pro601, I feel pretty confident in saying that a DJ2 is just an NP4 made out of the black oil-tanned leather, a basket web and tan laces.
This is correct and confirmed with a recent PRODJ2DS that I purchased for my son. It has NP Pattern stamped on it's thumb palm side. NP4 11.5 will get you a DJ2 without the stamp.