Josh's response with the link has answers:
http://www.4x4wire.com/toyota/4Runner/tech/suspension/

New technology to fix the sag? Let's see.
There ain't none.
You have: Mass produced coils, custom coils, air bags, and the leaf spring conversion <img border="0" title="" alt="[Wink]" src="images/icons/wink.gif" /> .
Oh, can't forget about spacers.

The write-ups are pretty recent. They were coordinated by Schaefer, a moderator of this forum, specifically to cover this top since it comes up all the time.
http://www.4x4wire.com/toyota/4Runner/tech/suspension/

Feel free to ask any question about the write-ups.
http://www.4x4wire.com/toyota/4Runner/tech/suspension/

Review them well. <img border="0" title="" alt="[Big Grin]" src="images/icons/grin.gif" />
http://www.4x4wire.com/toyota/4Runner/tech/suspension/

<small>[ 24 May 2002, 02:46 AM: Message edited by: code33 ]</small>