The 2mm coated aluminum spacer fits beneath the differential and slots/keys toward framework. You could spot 2 along side eachother to create 4mm spacer. The style is manufactured such method your 2 spacers will freeze position. With regards to the dishes use you may want to additionally spot out from the straight back stiffener. Increasing the rollcenter goes the differential greater aswell, creating more grip and steering, but less easy to drive.