PFF5-1322 Gearbox Mounting Bush Insert is made using Yellow 70A durometer material. It has been designed to fill the voids in the OE mount for an effective and affordable solution to stiffening the original rubber. It will not fit the GP3 model. As the vehicles age and simple upgrades seeing the 2-ltr turbo engine push power north of 250bhp, the OE rubber engine and transmission mounts are showing their age, with cracked rubber and excessive movement. PFF5-1322 Gearbox Mounting Bush Insert is made using Yellow 70A durometer material and has been designed to fill the voids in the OE mount for an effective and affordable solution to stiffening the original rubber.