I purchased quite a few of those systems when they came out of production and went into the surplus supply chain. I don't recall anything unusual about the cubes with NeXTDimension boards that were in there though. Some had two boards, which was outrageously over-the-top powerful. There were a lot of slabs that were also labelled "NRO", and I bought lots and lots of them. No hard drives, of course. There was a surplus yard in Maryland that had the contracts for the TLAs. Not open to the public, but if you spent enough and brought donuts, you could clamber across the content of that week's 18-wheeler crammed to the top with magical gear coming out of places that had unlimited budgets and fast replacement cycles. It was legendary. I still have a fax machine somewhere in my dusty piles with "Joint Chiefs of Staff - Whitehouse" property tags.