[HELP] Install Different Firmware on Samsung S III GT-I9300

Hello Guys Im new here. I'd like to Install different Firmware with same model (GT-I9300) on my device but
Im scare it will cause Hard Brick. Here is my device spec:

Samsung S III GT-I9300

AP: I9300XXUGNA5
CP: I9300DXUGNB1
CSC: I9300LBGNB1

Currently on my device installed firmware I9300XXUGNA5. Yesterday I rooted my device to use Custom rom but
still confused :confused: is it possible for me to install different firmware ? Like I9300XXUGNB6 ?

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