To examine the contents of a tarfile use the tar command. For example:
tar tvf project.tar
This will display the contents of the tarfile project.tar without unpacking the tarfile. See the manual page for details of the command options tvf.
To display the contents of a compressed tarfile use the zcat command. For example:
zcat project.tar.Z | tar tvf -
This will display the contents of the compressed tarfile project.tar.Z without uncompressing and unpacking it.