I answer your question.
Part number: 89911-X1025
Hardness =HV310-370.
Surface hardness =HV280-390.
Washer hardness =HV250-450.
The SKMT is not an official supplier of Toyota, it does not yet have the TS standard. (TOYOTA STANDARD)
TS standard was changed to the new version.
Inspection standards and drawings written in old standards, which are different in certain respects from those written in the new standard.
Inspection standards Meidoh is written in old standards.
PTMI has been written in the new standard.
SKMT will adopt the new standard.
However, certain parts drawing instruction takes precedence to the accompanying drawings.
The hardness of the washer is HV250-450.