I am doing one right now. Let's clear up some misinformation in the above pics too. The 69 boss 9 did not have exposed exhaust tips as the pic suggests. They ALL had a straight rear valence and turndowns. That applies for 70 as well. Secondly, no need to fit louvers to a boss 9. None were factory installed either year. Only interior color in 69 was black. The magnum 500s were different from 69 to 70. For a correct 69 wheel steal some from the Amt mopars. Tall center cap they had and different spokes. As far as engine size, the 70 engine fits just about right in the 69 Mach model.