These kingpins are designed for the ball cups on top which eliminates mistakes when assembling the old school associted top eyelet and pivot ball.  If you weren't careful, the traditional upper eyelet and pivot ball could cause a bind at the top (near the e-clip) if you didn't remove some extra material. The B3 kingpins alse reduce the items that can cause slop by half.   In order to use this, you must shave your steering block down, otherwise the B3 won't be long enough.  We do recommend B3 kingpins now for all cars.  We are shipping all new cars this way.