Which Ratio for your Mk? gerarbox? Mk 1, 2 & 3 gearboxes were addaptions of VW gearboxes, so few were made it is unlikely that you have one! If you do please contact Hewland SALES for advice. Mk 4, 6, 7, 8 were all fitted with MK8 gears as standard. Mk 5 gearboxes were fitted with MK5 ratios. New Mk 9 gearboxes can be fitted with either MK5 or MK8 ratios. It is also possible to fit MK5 ratios to Mk 4, 6, 7, 8 gearboxes and MK8 ratios to Mk 5 gearboxes. To Identify which you have measure the diameter of the layshaft. MK5 ratios use a 1.125 inch (28.58mm) laydhaft, MK8 ratios use a 1 inch (25.4mm) lashaft.