A way to find out old download links is to use internet archive tools like "Way back machine", https://archive.org/web/. You can browse older web pages versions and get the links you want.
For example, I needed to download the NDK rev 9, so I used this tool to access the NDK download page (https://developer.android.com/tools/sdk/ndk/) from March and the download link in March pointed to NDK rev 9.
