Like B.C. said there are only three door lock motors on the cars (four if you count the trunk/hatch motor). You need something to operate the drivers door lock. Fortunately Volvo designed the motor to fit either door (drivers or passengers). You will need the motor (make sure it is a two wire and that reversing polarity moves the plunger back and forth accordingly) the linkage and clip from the plunger, the pivot, the linkage that goes to the lock itself and four screws. Mine cost me about $25 USD at the local junkyard. Take the motor off it's bracket, reverse it and reassemble, same with the pivot. Shouldn't take more than thirty minutes to install.

There are several different brands of aftermarket motors that are cheaper but you have to figure out how to mount it and get the geometry right for the linkages. The junkyard option is a custom fit.

Bulldog security's website is:

http://www.bulldogsecurity.com/