Rears are 8" in overall length for the MSP. So if you do the calculations from my earlier post you'd need a rod that's 7.125" in length. If your car is lowered (non-MSP springs), then set your sway up parallel to the ground, while the car is on the ground, measure the distance from hole to hole, subtract .875 (if using aforementioned rod ends), and there's your rod length.