Level suspension question

['94IDITurbo7.3]

while i have been looking around ebay and cl for trucks i have noticed that some trucks even 4x4 sit nose down.

like this one.......
http://cgi.ebay.com/ebaymotors/CLEA...5463232?pt=US_Cars_Trucks&hash=item2c6229bbc0

i have seen others that sit nice and level like this one.....
http://battlecreek.craigslist.org/cto/2783239516.html

i know the cl link has an add-a-leaf but i have seen trucks that have factory supsension that sit level.

question:
why do some trucks sit level from the factory and some don't?

 

[trackspeeder]

Different spring codes will change the hight. For example, if the truck is set up with the plow package it will sit level.