The spacers will probably be the same exact design for top/bottom. I'll verify dimensions when I have Corey's apart this Saturday. Reason for going 1/2 top and 1/2 bottom is to ensure the spring is always captured and to facilitate installation. If I did 1" top, it would be a PITA to get the driver side spring back in. If I did 1" bottom, it would reduce the amount of remaining material that centers the spring/isolater.