All small blocks share same crank ?

Just because the tires are new and balanced doesn't mean they are not the problem. I just worked on my friends Lexus, he said it has a thump from the rear at 80 mph. I removed the rear wheels, 1 wheel was bent, and 1 tire was bad. He just had 4 new tires installed. Both rear tires were at least 4 oz. out of balance each.