The Z-OH-6 rims most likely wont fit a 3rd gen. without adapters/spacers as all of the dish on these rims are on the back side. But you'll at least be able to test this without buying first as your pal has them now.
They definitely need spacers, which is something im up in the air about. I really like them though. I did a lot of reading at thridgen.org about them, I think you can actually get 9 or 10 inch wide to fit in the back. As a matter of fact here is the link to the discussion, there some photoshop pics in there too.
http://thirdgen.org/techbb2/showthread.php?s=&threadid=273539