Okay, more info from Yakima. The Wing Mighty Mounts were sold one at a time or in sets of 4. The part numbers are of course different. Here's how it works: One horizontal wing mighty mount is part number 8830027. A set of 4 is 8003601. One vertical wing mighty mount is part number 8830028. A set of 4 is 8003600.

So, according to Yakima, 3601 will fit the Vehicross Wing Bar.

BTW, my Isuzu dealer says the part is available in the warehouse. You could check with your dealer if this auction doesn't work out.