It is not a bolt-in job. Much underbody panel work has to be done and it simply isn't worth it. You can just go buy a car with
IRS.
And I am a big fan of the Ford Watts link rear end over almost any other for weight, cost and effectiveness ... yet there is absolutely no way it comes near the AU
IRS. I have driven Jags, Mercs and BMWs (amongst others) and I can assure you the AU
IRS is right up there, and even better than most of them. It leaves the "control blade" and any Holden swing arm style lagging far far behind.