my 2001 s40 (80,000 miles) had developed a vibration problem. When I drive at 40-50 mph the front vibrates/shakes. Sometimes this occurs at 30mph. I got the tires balance, that didn't fix the problem. Took it to the volvo dealer, they said: - the front left/right drive axle shafts are worn and needs to be replaced (cost 00)(wow). took it to pep boys and after their inspection the mechanic said that the axles seem fine, maybe its a tranmission problem, they can rebuild both sides for under 0. Any advice on if it is an axle or tranmission problem. Thanks