I just measured mine and its about 1230mm wide. This was a pretty rough measurement as it is dark and I have had a few beers. But in saying that when I got my R31 diff shortened I got it 10mm wider each side than the stock diff. I did this so the wheels sat more to the centre of the wheel arch allowing me to fit slightly wider tyres. I got allot of help from PIGDOG with the measurements so you should shoot him a PM. My diff it in a 1200 ute if this helps.