Mac OS 7.5.3d3c2

System 7.5.3D3C2 is a development build of System 7.5.3.

Disk Tools (68k only)
The 68k version of Disk Tools disk of this build is very unstable, and the Finder will crash for illegal instruction. Therefore, it is recommended to use System 7.1's Disk Tools disk to initialize the hard drive.