The 52xx/62xx Diagnostic Utility was made available to detect an issue with a small number of PowerPC 603 microprocessors used in ONLY Macintosh Performa 5200, 6200, and Power Macintosh 5200/75 LC computers. Only computers within a specific serial number range were potentially affected by this issue. The Diagnostic Utility was posted on the online services, but it has since been removed with the posting of the 5xxx/6xxx Tester.
The 5xxx/6xxx Tester should be used to test for known component issues that may cause system freezing in ALL Power Macintosh and Performa 5200, 5300, 6200, and 6300 series computers, including the Apple Power Macintosh 5200/75 LC and 5300/100 LC, and Macintosh Performa 5200, 5215, 5300, 6200, 6205, 6214, 6216, 6218, 6220, 6230, 6290 and 6300. (The recently introduced Power Macintosh 5260 and 6320 are not included in this program because Apple corrected all the known issues with this product prior to manufacturing.) The 5xxx/6xxx Tester is available on the online services.
These articles can help you locate the software update mentioned here:
Other References:
The following Tech Info Library articles provide additional information on the 5xxx/6xxx Tester application and related issues.