Another way to check the rear axle. Tie a string off to one wheel, pass it thru and under the brake drum. Pull the string across, under the brake drum and thru the other wheel. Tie the loose end of the string off. Make sure the string is at the bottom of each brake drum. Measure up from the string to the bottom of the axle tube, taking measurements at the drum end and the diff ends, both sides. Compare side to side measurements, should be the same, or very close to it. I don't know what the manu tolerances were new, but I would think anything more than 1/16 inch indicates a problem. On the front, use a small (torpedo) level on the sides of the frame to check for twisting. I read your post bout the runaway. Its enough to make ya cry.