Some questions about the z-levels and the loot crates

[Riffhunter]

Thank you all for the responses. I still have one more question, for which I maybe get yelled at so let me apologize before hand :__). How do I know what is a syndicate surplus crate and how do I obtain it? In the uplink the only available options are the same for traitors and nuke ops, but there are some items listed in the syndicate surplus crates that are not available.