Nothing classified Things like the SPN-41 are definitely far out of production (those cards are literally through-hole construction with discrete components an

Nothing classified Things like the SPN-41 are definitely far out of production (those cards are literally through-hole construction with discrete components and DIPs for ICs), Possibly SPS-48/49, lots of combat systems equipment, etc. There are tons of things like that where the contracts to build them ran out decades ago. I suppose I shouldn't say totally irreplaceable, the government will contract with someone to go back and build new ones if they have to in order to outfit, but the process to do so would be so cost prohibitive it would be smarter to just create a whole new system. Imagine systems where the entire worldwide demand is less than 25 systems (one each for the CVNs and LHD/LHAs), all of them were built in the 1980s/1990s, and all of them were essentially hand built then. Nobody can profitably keep a production line open for them, even spares are built and provided with the systems at delivery. So if you need a new one, you're kind of screwed. You either have to go back and pay a huge premium and hope the original company (if it exists, and sometimes it doesn't) can replicate their decades old work and build you a new one, or you have to contract to develop a new system. Kind of a catch-22 -- both are prohibitively expensive. We had systems on my first boat in the 90s that had been built in the 60s and continually refurbished and upgraded since, no new ones had been built since the 70s and 80s. You can tell by the serial numbers.