Can you give me the exact date and time that Sai Baba left his body, based on the details in Chapter 42?

Yes, Chapter 42 provides very specific details about Sai Baba's passing. It occurred in the Shaka year 1840, during the first month of the sun's southern transit (Dakshinayan). The day was Vijayadashami, which is also Dussehra. The text further specifies that this corresponded to the 9th day of the Muslim month, on the night of 'Kattal' (the eve of Moharram). The time of his departure is noted as the third watch of the day. The chapter clarifies that while the day is considered Dussehra, the actual moment of his passing was just after 12:30 PM, when the Dashami tithi (lunar day) had completed and Ekadashi had just begun.