The fun part here is that I have two different tars and two different gzips - the ones supplied with the OS and "SGI freeware" variants installed on /usr/freeware (dowloaded from http://freeware.sgi.com/)

Do not use the OS supplied tar! You'll hit a bug.

I've installed the freeware version a while ago (GNU tar) 1.13.25
without an itch along with /usr/sbin/gzip.

Both incarnations of gzip return the same version string as the one you included above

/usr/freeware/bin/tar is

tar (GNU tar) 1.13.25


Not sure how to get version string from /usr/bin/tar, but I have

# uname -R
6.5 6.5.16f

Based on the dump file headers, I would assume that /usr/freeware variants are used for both tar and gzip. Actually, maybe that one is *required* by Amanda, since it wants GNU tar, and the one on /usr/bin is not, as far as I can tell. Perhaps there wasn't really any point in installing "freeware" version of gzip, or will Amanda make assumptions about binary locations?

Check your amandad debug files and look at the paths and defs

The one on the server is gzip-1.3.3-9 from Red Hat.

and check for GNUTAR="/usr/freeware/bin/tar" ,
COMPRESS_PATH="/usr/sbin/gzip" and UNCOMPRESS_PATH="/usr/sbin/gzip"

Mine has:

amandad: paths: bindir="/opt/amanda/amanda2/bin"
amandad:        sbindir="/opt/amanda/amanda2/sbin"
amandad:        libexecdir="/opt/amanda/amanda2/libexec"
amandad:        mandir="/opt/amanda/amanda2/man"
amandad:        AMANDA_TMPDIR="/tmp/amanda-conf2"
amandad:        AMANDA_DBGDIR="/tmp/amanda-conf2"
amandad:        CONFIG_DIR="/opt/amanda/amanda2/etc/amanda"
amandad:        DEV_PREFIX="/dev/dsk/" RDEV_PREFIX="/dev/rdsk/"
amandad:        DUMP="/sbin/dump" RESTORE="/sbin/restore" VDUMP=UNDEF
amandad:        VRESTORE=UNDEF XFSDUMP="/sbin/xfsdump"
amandad:        XFSRESTORE="/sbin/xfsrestore" VXDUMP=UNDEF VXRESTORE=UNDEF
amandad:        SAMBA_CLIENT=UNDEF GNUTAR="/usr/freeware/bin/tar"
amandad:        COMPRESS_PATH="/usr/sbin/gzip"
amandad:        UNCOMPRESS_PATH="/usr/sbin/gzip" LPRCMD="/usr/bsd/lpr"
amandad:        MAILER="/usr/sbin/Mail"
amandad: listed_incr_dir="/opt/amanda/amanda2/var/amanda/gnutar-lists"
amandad: defs:  DEFAULT_SERVER="bullcalf" DEFAULT_CONFIG="stk_40-conf2"
amandad:        DEFAULT_TAPE_SERVER="bullcalf"
amandad:        DEFAULT_TAPE_DEVICE="/hw/tape/tps12d2nrnsv" HAVE_MMAP
amandad:        HAVE_SYSVSHM LOCKING=POSIX_FCNTL SETPGRP_VOID DEBUG_CODE
amandad:        AMANDA_DEBUG_DAYS=4 BSD_SECURITY USE_AMANDAHOSTS
amandad:        CLIENT_LOGIN="amanda" FORCE_USERID HAVE_GZIP
amandad:        COMPRESS_SUFFIX=".gz" COMPRESS_FAST_OPT="--fast"
amandad:        COMPRESS_BEST_OPT="--best" UNCOMPRESS_OPT="-dc"

Mine is:

amandad: paths: bindir="/usr/freeware/bin" sbindir="/usr/freeware/bin"
amandad:        libexecdir="/usr/freeware/libexec"
amandad:        mandir="/usr/freeware/man" AMANDA_TMPDIR="/tmp/amanda"
amandad:        AMANDA_DBGDIR="/tmp/amanda"
amandad:        CONFIG_DIR="/usr/freeware/etc/amanda"
amandad:        DEV_PREFIX="/dev/dsk/" RDEV_PREFIX="/dev/rdsk/"
amandad:        DUMP="/sbin/dump" RESTORE="/sbin/restore"
amandad:        XFSDUMP="/sbin/xfsdump" XFSRESTORE="/sbin/xfsrestore"
amandad:        GNUTAR="/usr/freeware/bin/tar"
amandad:        COMPRESS_PATH="/usr/freeware/bin/gzip"
amandad:        UNCOMPRESS_PATH="/usr/freeware/bin/gzip"
amandad:        MAILER="/usr/sbin/Mail"
amandad:        listed_incr_dir="/usr/freeware/var/lib/amanda/gnutar-lists"
amandad: defs:  DEFAULT_SERVER="localhost" DEFAULT_CONFIG="DailySet1"
amandad:        DEFAULT_TAPE_SERVER="localhost"
amandad:        DEFAULT_TAPE_DEVICE="/dev/null" HAVE_MMAP HAVE_SYSVSHM
amandad:        LOCKING=POSIX_FCNTL SETPGRP_VOID DEBUG_CODE
amandad:        AMANDA_DEBUG_DAYS=4 BSD_SECURITY USE_AMANDAHOSTS
amandad:        CLIENT_LOGIN="amanda" FORCE_USERID HAVE_GZIP
amandad:        COMPRESS_SUFFIX=".gz" COMPRESS_FAST_OPT="--fast"
amandad:        COMPRESS_BEST_OPT="--best" UNCOMPRESS_OPT="-dc"
amandad: time 0.002: got packet:

HTH
jf