Yeah, you can do one side only....but why would you want to? If the one side rusted out and failed then it's only a matter of time until the other side does the same. Would you like that to happen at 60 mph? I say do both of them. I did. I had an 83 240 turbo when I lived in New York about 6 years ago. The car was a NY/NJ car it's entire life. In fact, I lived in Orange County NY but worked in Bergen County NJ. I drove the 60 miles each way 5 days a week in that 240 turbo. One day (and I kid you not) I decided to take the back way into work and I got off route 17 an exit or two early so I could take a less traveled road that ran by Teterboro airport. Good thing I did. My drivers side front strut assembly collapsed due to rust and it came down directly onto my front tire stopping the car as though I was an F-14 slamming onto the deck of an aircraft carrier. Fortuntately for me, I was only doing about 25 mph on a 2-lane road. Has I been on route 17 doing 65-75 with the rest of the traffic I could have had BIG trouble. I had a mechanic I found down there replace the one strut assembly and asked if I wanted the other one done since it was pretty rusty as well. It wasn't even a no-brainer. I interrupeted him by saying "Just do it please." Out here in California, where I now live, things like this rarely happen because there's not any rust on cars that have spent their whole life out here. My current 82 240 Turbo is entirely rust free. I traveled back to NY about 5 months ago on a visit and let me say this: I think the old 240 series from the early 80s is all but extinct there, rust having taking its toll and corroding them into oblivion. The few copies you do see on the road look really, really bad, the rust having eaten away the rear wheel wells by the mud flaps, the rear edges of the tailgates, the bottoms of the doors, the door jams, the floorboards.....basically the whole damned car. Too bad Volvo didn't dip them in zinc like they finally did on the later 700/900 series vehicles. There's still plenty of *those* around in the Northeast. The 200 series reminds me of all the old VW Beetles my father had owned down through the years. The engines would still be going but the body and frame would just rot away. Makes me feel sad that the 240 series, which may be the best built Volvo ever (structurally speaking), has been doomed to the same fate. In short, it would probably be a wise move to have the other strut assembly replaced, but it's your call.