Here you can download Spreadtrum SC7710 based PAC Stock Firmware for the Micromax A66 Android device. The downloadable file High Compressed in an archive, You will get the Flash File after extraction. Included contains Flash Tool, USB Driver, and how-to Flash manual instructions.
[*] Chipset: Spreadtrum SC7710G.
[*] Driver: SPD SCI Android USB Driver.
[*] Flash Tool: SPD Upgrade Tool.
Firmware for Micromax A66
Build Number: GST_A93_W862_MMX_A66_44_V21
Android Version: v4.1.2 (Jelly Bean)
Download Size: 181 MB
Micromax A66 Flash Tool & USB Driver
Flash Tool for Micromax A66
Micromax A66 USB Driver
[*] Backup: During the flashing process SPD Flash Tool will erase user data from the phone. So you need to backup for restoring those files on your device.
[*] Device Information: The Micromax A66 phone powered by Spreadtrum SC7710 CPU. So you need to use SPD Flash Tools and SPD USB Driver to flash Firmware on this device.
[*] Flashing Information: You can try different types of SPD Flash Tools to flash this Pac file if you see any of them show interrupted in flashing. The following Tools are Upgrade Download, Research Download, and Factory Download.