System 7.5 Update 2.0 Custom Install -- If you've upgraded to System 7.5.5 (see TidBITS-346) and later found that you needed to re-install something from System 7.5 Update 2.0 (which upgrades System 7.5 to 7.5.3), you discovered that System 7.5 Update 2.0 won't run under System 7.5.5! Apple routinely does this with system software installers to ensure users don't unwittingly mix-and-match system components that were never designed to work together. However, with the plethora of Mac clones, system revisions, and updates lately, not being able to install components of the System 7.5 Update 2.0 under 7.5.5 can be troublesome - users particularly need to get Open Transport 1.1, MacinTalk, or other components from System Update 2.0.
Apple's supported solution is to do a clean install of 7.5.3 with whatever additional components you need, then upgrade to 7.5.5 again. However, Apple is also providing an unsupported updater installer script that you can use with System 7.5 Update 2.0 under System 7.5.5 by dragging the script to the 7.5 Update 2.0 installer icon. Back up your system, turn off all non-7.5.5 extensions, and read the instructions first! Although this script may be overshadowed by future component releases (such as Open Transport 1.1.1), reports that many computers may not ship with System 7.5.5 for some time may give this installer script a long lifetime. [GD]