They are from an A3 quattro or mk4 golf 4 motion Part number is 1J0 615 611 C / 1J0 615 612 C, the two part numbers correspond to the position of the ABS sensor hole but that does not matter in this instance since the VR6 ABS sensor is perpendicular to the driveline. I pick these ones just because they looked the closest match to the originals.
Then I traced the mounting holes from the originals over to the new ones made a jig to mount it on and cut away with a pad saw and a die grinder. Sorry for lack of pictures of this operation, but this is the end result after paint and lacquer:
Look pretty neat and fit perfectly with mk4 calipers!