I noticed torque boxes on the front. Did you add those?
In '70, all U-code, V-code, R-code, convertables, AAR/TA's were "supposed" to come with the torque boxes standard. There is no "option" code for them as far as I am aware. I have owned 440 cars that had the rears, but no fronts. I have seen many Los Angeles built '70 'Cuda and Challenger RT 340 and 383 cars that have the front torque boxes factory installed. That may have been the standard at that plant.