If you lost this screw, must find 1 replacement back, eventhough this screw isn't the main one to hold alternator in correct position, but it does catching the alternator tight so that it is grounded properly together with engine block.

Bro replied, and will upload it later.
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Oh i read that too fast, yeah you're right. No problem by unscrew it to hold the GC cable, coz you can try even you unscrew it out and when you try to force move the alternator, you won't be able to  because there are other mounting points down there still.

This screw need special tool to open, normal wrench is very hard to open. I can help you open it and install that cable, pls let me know around when you're able to come to puchong ?