^^^ WHS, on the left side of the gearbox bell housing there is a large allen head bung screw. Undo that and screw a 10mm (M6) bolt into the end of the pivot pin inside, slide the pin out, then lift the clutch fork up until it disengages with release bearing. THat may be whats stopping the engine coming away. I've seen some one break the bell housing trying to remove the box without doing this, and I've also seen some one destroy the clutch pressure plate.

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F.B. Racing
01 WRX (STI badged)
2010 XR5 Focus
06 Impreza Hatch 2.0i