WARNING: This page is about a different car, the 2004 Volvo S40, 2003 Volvo S40, 2002 Volvo S40, 2001 Volvo S40, and 2000 Volvo S40. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Single Or Double Cavity Row
Courtesy of VOLVO CARS OF NORTH AMERICA.
There are two main types of 0.64 isolators.
See contact side of the isolator.
Does the isolator have a single or double cavity row?