To get your new tensioner on you need to remove the fan pulley,water pump pulley and steering pump pulley. This will give you access to remove the Y pulley as shown.
You need to loosen the 19mm bolt holding the tensioer on.
Remove the tensioner shock.
Be careful when adjusting the tensioner. There is a DIY on how to adjust this in the DIY section
Otherwise this may happen
You can now remove the 19mm bolt and remove and replace the tensioner