Hi, I have a question regarding ball joint replacement on a 1999 Bravada. When I was driving home from work today, the upper ball joint on the front right side gave out and the tire caved inward. The car is at the mechanic now and he said he would replace the two worn (upper) ball joints on the front wheels for $500. But isn't it true that you should have BOTH the upper and lower repaired for each wheel that has an issue? In my case, the two front tires. So really it's a total of four ball joints for...