spiceyokooko's words sound harsh but the OP should follow that advice.
There is no need, most of the time, for a third party extensions manager. It comes free with System 7.5 onwards, and that version can be retrofitted to System 7.0 onwards or you can dig out the version that Apple offered on the developers site. If you have System 7.5, Extension Manager is usually good enough. The third party products may "fix things" but you may not understand what has been fixed.
For System 6, try John Rotenstein's freeware "init cdev".
When installing Mac system software, expect that a universal installation will work on a standard model. Apple tried it and tested it. If your Mac has a third party accelerator, use the option "Install System Software for this Mac" and then run the installer/drop in the CDEV/INIT.
Add lightness and simplicate.
There is no need, most of the time, for a third party extensions manager. It comes free with System 7.5 onwards, and that version can be retrofitted to System 7.0 onwards or you can dig out the version that Apple offered on the developers site. If you have System 7.5, Extension Manager is usually good enough. The third party products may "fix things" but you may not understand what has been fixed.
For System 6, try John Rotenstein's freeware "init cdev".
When installing Mac system software, expect that a universal installation will work on a standard model. Apple tried it and tested it. If your Mac has a third party accelerator, use the option "Install System Software for this Mac" and then run the installer/drop in the CDEV/INIT.
Add lightness and simplicate.