Não consigo encontrar uma maneira de obter uma versão mais antiga de um pacote
Não existe um arquivo completo de pacotes antigos.
If you really need an older package, you may be able to find an outdated or archival mirror by searching the web for an old package version (for example, gcc2-2.95.3-10-src.tar.bz2), but keep in mind that this older version will not be supported.
Posso usar o Cygwin Setup para obter versões antigas de pacotes (como o gcc-2.95)?
Cygwin Setup can be used to install any packages that are on a Cygwin mirror, which usually includes one version previous to the current one.
The complete list may be searched at https://cygwin.com/packages/.
There is no complete archive of older packages. If you have a problem with the current version of a Cygwin package, please report it to the mailing list using the guidelines at https://cygwin.com/problems.html.
That said, if you really need an older package, you may be able to find an outdated or archival mirror by searching the web for an old package version (for example, gcc2-2.95.3-10-src.tar.bz2), but keep in mind that this older version will not be supported by the mailing list and that installing the older version will not help improve Cygwin.