There is no official "Service Pack 3" for Windows Server 2008. However, because Build 6003 looks like a major version jump, some community members and third-party scripts refer to it as a "de facto SP3".
Standard extended support ended January 14, 2020. Paid Extended Security Updates (ESU) for on-premises servers ended in early 2023, though some Azure-hosted workloads received support until January 2024 . windows server 2008 build 6003 upd
Type winver in the search bar or command prompt to see the version string. Use WMI: Execute wmic os get version in the command prompt. There is no official "Service Pack 3" for