These kits will require drivetrain modifications.Your driveshafts will need to be lengthened and a combination of steering components will be needed to correct the steering angles. Longer brake lines are a must, sway bars need lowered, and sometimes additional axle shimming to get the alignment correct. These kits bolt right on with normal hand tools, but do require more labor than the smaller kits. Some of the kits come with all or some of the components needed, so be sure to check out what is included in each kit carefully The 8" kits are available as a KIT, with rear blocks, or as a SYSTEM that features new replacement rear springs. The 10" and 12" kits are SYSTEMS that use new rear springs.8" KitsRecommended Maximum Tire Size:38x15.50 on 10" wheelsAdditional Required Components: Steering Arm / Pitman Arm / Sway bar lowering kit / Brake Lines10" KitsRecommended Maximum Tire Size:40x17.50 on 10-12"" wheelsAdditional Required Components: Steering Arm / Pitman Arm / Adjustable draglink/ Steering block/ Sway bar lowering kit / Brake Lines12" KitsRecommended Maximum Tire Size:42x18.50 on 10-12" wheelsAdditional Required Components: Steering Arm / Pitman Arm / Adjustable draglink/ Steering block/ Sway bar lowering kit / Brake Lines