I think I bought mine directly from energy suspension. It's a little tough to navigate thier site but I bought an entire body kit that has everything including spring bushings, sway bar bushings etc. You can get just a body kit too.
Edit: Heres a link
http://www.energysuspensionparts.com/products.asp?cat=Ford+F350+4WD+1992
Website has been updated and is nicer now.
Edit: Heres a link
http://www.energysuspensionparts.com/products.asp?cat=Ford+F350+4WD+1992
Website has been updated and is nicer now.
