Not sure exactly what Yakima part you are talking about, but here it goes...

The cross bars are still available from your Isuzu dealer (hurry). These bars attach to the standard factory rails. They were made by Yakima. Yakima had their own at one time (wing bars), it has been discontinued for some time.

Contact St. Charles Isuzu (use the search feature) or go to isuzuparts.net and send them an email. They will set you up with a set. Both places will most likely charge less than what your local dealer would ($348).

Once you have these cross bars, you can attach just about all Yakima products to them with the use of various brackets and adpters from Yakima (like mighty mounts etc.)