tkman, tkinfo, TkDesk and tkdiff are Tcl/Tk-based applications which require at least version 7.6 of that scripting language. They can be obtained from the Tcl/Tk archive at http://www.neosoft.com/tcl/ftparchive/sorted/packages-7.6/ in the subdirectories /text and /file.
Another Tcl/Tk-based application, tkzip, has a home page at http://www.pcnet.com/~proteus/TkZip/TkZip.html.
xtar and mgdiff are Motif-based applications. In the unlikely case that the Motif libraries are installed on your system, you can download the source codes from ftp://ftp.ienet.ie/pub/X-contrib/applications/ and compile the programs with the included Makefiles. Ready-to-run binaries should be available from ~/RedHat/motif/RPMS/i386/xtar-1.4-1.i386.rpm and ~/RedHat-contrib/grouped/libc5/i386/X11/Utilities/mgdiff-1.0-1.i386.rpm, where the ~ stands for ftp://ftp.archive.de.uu.net/pub/systems/Linux/Distributions.