WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. 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?