Sort of unrelated, but I had a 70 skid plate k-member, v-8 non hemi, with a 70 383 non skid plate part number and 70 model year date code. Was in a 69 383-4bbl charger that had one 70 sway bar lower control arm and one 69 sway bar lower control arm. 69 Charger had 69 bendix disc brakes too. Could it have been an over the counter replacement from a collision repair? Not rusted at all and under the black paint was a grey paint.