If your DIYing it at home I would take the engine out as those gearboxes are heavy.. especially if your working on a Quattro... a garage however using a ramp would do it from underneath and just drop the box.... I would change the dual mass flywheel too as they fail after a while infact it was the flywheel that started failing on mine before the clutch.... I was also advised to steer clear of a single mass conversion on a Diesel due to the extra vibrations transmitted into the gearbox from the Diesel Engine,,, there's a reason Audi fitted Dual Mass in the first place.... single mass ones have been known to munch the gearbox... i think this is less of a problem on petrol engines