The passenger side is lower. On that side, I was able to just weld the bushing sleeve to the top of the frame rail. On the drivers side, I had to weld a tab to the frame so that I could center the hole saw and cut pretty close to half, maybe 3/4 of the hole into the frame. It's a about an inch difference. My sleeves were 1.75, so I slid a piece of 1.5 through them to line them up before welding.