STRANGE axel twisted?

You only leave the line at 2000 rpm in the 66, and you twisted the axle, i say cheap metal also, when my car was a340, 4 speed i lunched at 3800-4200 with the 340,auto and trans brake 4400, with the 416 deal , i foot brake it,(trans brake leaves to hard with super stocks springs) and still i leave above 3500 rpm.