The MIB88 megamod is currently version 2.34. This latest version contains some new content, but mostly corrects errors from previous versions of this mod. Also, the worldmap in this version is larger. See also the Megamod FAQ.
THe mod MIB88 has been working on for years, adding new content to Fallout 2. Make sure and run ProcessDat2.exe before playing, not doing that will cause error when saving. Manual install package.