sunsite.icm.edu.pl looks to be an old mirror of the pre-Oracle Sunsites. It’s quite useful for patches for older Solaris releases.
To get Internet Explorer 5.0 for Unix (Sparc) running on the Sparc release of Solaris 7 I ended up using:
108376-46: OpenWindows 3.6.1: Xsun Patch (Patch File)
106327-23: SunOS 5.7: 32-Bit Shared library patch for C++ (Patch File)
106950-24: SunOS 5.7: Linker Patch (Patch File)
And voila! Internet Explorer 5.0 for Unix running on the Sparc release of Solaris 7.0