This is the recommended by CrackBerry forum experts. The autoloader is for all Z10 Qualcomm models (STL100-2/3/4):
Follow these steps carefully to flash the BlackBerry Z10 STL100-2 with the 10.3.3 autoloader. Step 1: Download the Correct Autoloader Blackberry Z10 Stl100-2 Autoloader 10.3.3 Download
Use 10.3.3.3216 (OS version) / 10.3.3.2137 (software release) for the most stable experience. This is the recommended by CrackBerry forum experts