The Volvo belt #966978 is suppose to be 1100mm long and 9.5/10 mm wide.
Gates has a belt #7430 that is the same dimensions and the Goodyear Gatorback 11AV1105 is 1105mm long and 11mm wide. It sits a little higher in the pulley do to the extra width and is 5 mm shorter than Volvo's belt. I've had good luck with both brands.
Mike