The yakima railgrabs may not fit, but the thule ones should because I think they have specific grabs for differing rail profiles. But even for the square thule bars, it's pricey. If the volvo works for you, it's definitely the least costly. There were some for sale a few months ago in the classifieds for V50s. Tasca and Volvo of Lisle both have new for around $170 for the alum wing profile ones http://volvopartslisle.com/part/OEM-Volvo-Part-31213964/Load-Retainer which is a pretty great price compared to Yakima/Thule.