It all depends on what springs you add to the rear pack.  If you put the rear pack in by itself then it will sit flat or negative.  You have to add springs to give you the lift you want.  Here are some links to go to.

http://www.pirate4x4.com/forum/showthread.php?t=265669

http://board.marlincrawler.com/index.php?topic=9254.0

http://board.marlincrawler.com/index.php?topic=8086.0

There are more, but if you go to the search button up top then you can search for more.