what year/model is the MK3?
At the front if its a pre-96 non-GTI then it'll have MK2 top mounts anyway, and will be a direct fit. If its a GTI or post-96 MK3 and you fit std type spring setup then you either need to fit a special 'heavy duty' upper spring mount from an early MK3, or just fit MK2 top mounts. At the back its all a direct fit.
If you have coilovers then chances are they'll work with either top mount setup regardless anyway
