so i took my 95 lwb in to fix another o2 sensor and i told the mechanic my situation with the vibration cuz its gottin worse theres slight cherping and when i hit about 30 mph the noise is loud and the vibration is worse until about 75 then it quites down. he hasnt had a chance to look at it but he thinks it might be a bad u joint.?? i havent had the tires rotated and the front right tire is a different brand(three goodyear forteras and one big o tire)coulr this be that simple of a solution?