On some early 997 models (pre-2006) there is no support on the outside face of the link arm to the hub bush.
For these models use 4 x PFR57-508 for the link arm to hub bushes & 4 x PFR57-509 for the link arm to the subframe bush. For hub carriers with support on either side of the bush, use 8 x PFR57-509.
PFR57-508 fits 22mm width arms, for 19.5mm width arms please use PFR57-1508.
PFR57-531 fits 996 & 997 vehicles with the twin gearbox mounting bracket (OEM part number 99737503303) at the end of the gearbox, as fitted to all 3.6 & 3.8 Tiptronic models, Turbo models Manual & Tiptronic, GT2 & GT3.
PFR57-532 Fits Gen 1 manual with a single gearbox bush in the end casing except for Turbo GT2 & GT3 models.
PFR57-533 Fits Gen 2 manual and PDK with a single gearbox bush in the end casing except for Turbo GT2 & GT3 models.