torque may result in them compressing different, but if they're both equally tight, I'd expect the only thing that would cause the difference [assuming they started out the same] is oil saturation, which can deteriorate rubber ... the rear mounts need that plate under the bolt [U shape if I remember right], it's a 2 piece deal - I'd get new, but original rubber, the poly ones squeek in time ... it could be a combination of front and back giving an uneven stance to the driveline, affecting the front U joint
Bill
