My '92 Silverado 1500 V8 5.7L has a vibration problem. Between 65-75 I receive vibration from the front end. The tires are brand new and balanced, and I have had a 4 wheel alignment done. The idler arms have recently been replaced also. My dad thinks it is the ball joints. Has anybody had this problem before? or does anybody know how to solve it and/or what it is?