After some serious searching, I came across thisSoftware Release Quick Lookup Table from Xerox. It lists all of the latest General Releases and Security Patches for each Xerox model, along with the download link for each one. It lists the normal firmware versions that you can easily find online, as well as the SPAR versions that are not so easy to find online.
We have a WC 5875i that is currently running software version 073.190.075.34540. We are running into problems when scanning to our newly added network storage. I believe the issues we are experiencing are being caused by the system software on the copy machine/printer. I understand an updated firmware version has been released, but the most recent one I can find online is the version I am currently running. Can you verify if there is a newer version available, and if there is, can you point me in it's direction?