The JR Motorsports rear must have two parts welded to it. JRM doesnt know where you might locate the springs. Therefore, you will need to weld the mounts to the housing. Weld horizontally on each side, not across the ends. If you weld the same amount on both sides, the housing will still be straight. Notice I cut down the height of the spring mount by 3/4 inch for ease of changing springs. I change the spring rates often.