Fitted this yesterday too - easy job really, as Kwempe kindly pointed out 
Whilst i had the front wheels off for the pads, i merely removed each ARB arm using a cross driver thingy and a pair of mole grips... (pain in the back side!) Then with both sides disconnected, i got under the car and undid the four nuts securing the old ARB - couldnt really see a massive difference between the two to be fair - they had different part numbers on the rubbers though so i presume they are different
Whilst i had the front wheels off for the pads, i merely removed each ARB arm using a cross driver thingy and a pair of mole grips... (pain in the back side!) Then with both sides disconnected, i got under the car and undid the four nuts securing the old ARB - couldnt really see a massive difference between the two to be fair - they had different part numbers on the rubbers though so i presume they are different

