[SOLVED] Recovering data in a very old, possibly corrupted tar archive?

Hi all,

There is a tar.gz whose contents I would like to access. The file itself is quite old, last being updated ~20 years ago if I had to guess (I am not sure if this is relevant). The file contains legacy scientific code that I would like for archival purposes and can be found via the "code site" link here. However:

• When I download the file and run tar -xvzf radpack.tar.gz I get an error: tar: Error opening archive: Unrecognized archive format.
• Likewise, if I try to gunzip it I get gunzip: radpack.tar.gz: not in gzip format.
• Running file radpack.tar.gz only yields radpack.tar.gx: data, indicating file cannot find anything out about it.
• head radpack.tar.gz outputs a string of unintelligible unicode.

These are the different solutions I have come across after searching this problem, and to me is good evidence that the file has been corrupted in some way and that may very well be the case. However, for archival and historical purposes it would be great if I could access the contents, so I am compelled to search out other solutions. Are there other options I can try here? Is there some way to confirm that the file is in fact corrupted beyond recovery? Any help on this point would be greatly appreciated. I posted this on stack exchange as well but figured maybe the smart folks here might know.

EDIT:

Just to be clear this has been solved — a functioning copy of the archive was found.