content: They might not have it or all of it in a format they can share. They'd usually print it out and shove it into a big fat hard plastic binder as their long term archive, eventually the digital copy might have been erased, destroyed or archived on some now defunct format that is either dead (bit rot is a thing) or just two awkward and unreliable to pull the information off of it.  That or MS doesn't actually own all of the 3.x code, could have weird 3rd party drivers or some other 3rd party pieces of software they just don't want to go though.