If you want longer Wing bars, try here:
http://store.yahoo.com/rack-warehouse/y0309c.html

I got a set from them last year. Looks like they still have some. You'll still need the custom Isuzu towers to attach the longer bars to the VX roof.

These longer bars *with* towers are cheaper than just the short bars from Isuzu. Even if you don't want the longer bars you might save some $$$ buying these and shortening them with a hacksaw. I did that with my first set of 58" bars when I couldn't find 48" anywhere.

-Daver