Just as promised. Here’s the official FTF file of the Android 4.4.4 KitKat firmware (14.4.A.0.108) for your Xperia Z Ultra C6833 (International LTE variant) phone. This FTF has been extracted from Sony PC Companion using Flashtool. It comes under Customized MY (Malaysia Generic) branding. Rest of the firmware details, official changelog  and direct download links are given below.
