I know this thread's from 2014; I just thought I'd add this info in case anyone searches GH for this part number.
IBM (in 1991) and Lexmark (in 1992) used this p/n for SSKs. Also in 1992, Lexmark oddly used the same p/n for the standard 101-key Model M's they made for court reporting systems made by an OEM called Reply:
One of these recently sold on eBay, hence the photos. Interestingly, the OEM logo appears in a square in the upper right corner—the same size, shape and location where the silver IBM logo appears on 1st-generation IBM Model Ms... Were any other later M's like this?
This also begs the question: How on earth could court reporters use buckling spring keyboards without distracting the heck out of everyone present? (I'm guessing the OEM wasn't around long, for that reason...?)