Scott,
Any update on your conversion? I have the same problem with my 2004 RX 330. It has been stuck on high for quite a while now. A collegue of mine told me that his RX 330 is starting to click. We both are interested in converting to struts. Here is a link to the GX conversion kit struts:
http://www.strutmasters.com/lexus-suspension-parts-s/22.htm
Thanks,
Brian