> I only have versions 2.2 of ZIP [...]

   Eeewww.

> [...] and 5.52 of UNZIP here.

   Slightly better, but not very much.

> Where can you pickup zip31 and unzip61 from?

   Those DCL symbols were ZIP3L and UNZIP6L, not zip31 and unzip61, and
were only large-file-capable builds ("L" for "large") of the current
released versions.  (I tend to have multiple versions of these programs
available here, so my DCL symbols tend to be more complex than those of
a typical user.)

   For files and archives bigger than 2GB, you normally need Zip 3.x and
UnZip 6.x.  When built with large-file support enabled, the "-v" reports
should mention LARGE_FILE_SUPPORT and ZIP64_SUPPORT:

alp $ zip3l -v
Copyright (c) 1990-2008 Info-ZIP - Type 'zip "-L"' for software license.
This is Zip 3.0 (July 5th 2008), by Info-ZIP.
[...]
Latest sources and executables are at ftp://ftp.info-zip.org/pub/infozip,
as of above date; see http://www.info-zip.org/ for other sites.

Compiled with DEC C V7.3-009 for OpenVMS (V7.3-2 Alpha) on Jul  6 2008.

Zip special compilation options:
[...]
        LARGE_FILE_SUPPORT   (can read and write large files on file system)
        ZIP64_SUPPORT        (use Zip64 to store large files in archives)
[...]


alp $ unzip6l -v
UnZip 6.00 of 20 April 2009, by Info-ZIP.  Maintained by C. Spieler.  Send
bug reports using http://www.info-zip.org/zip-bug.html; see README for details.

Latest sources and executables are at ftp://ftp.info-zip.org/pub/infozip/ ;
see ftp://ftp.info-zip.org/pub/infozip/UnZip.html for other sites.

Compiled with DEC C V7.3-009 for OpenVMS (V7.3-2 Alpha) on Apr 29 2009.

UnZip special compilation options:
[...]
        LARGE_FILE_SUPPORT (large files over 2 GiB supported)
        ZIP64_SUPPORT (archives using Zip64 for large files supported)
[...]


   Any Web search engine (or even your old "[Un]Zip -v" reports) should
be able to lead you to Zip and UnZip source kits (or obj+exe kits, if
you lack a C compiler).