I've got a disc brake set up I believe is from a '72 'Cuda, but not sure. I'd like to put them on a '70 power drum 'Cuda. What's the diference between the early ('70) disc set ups and the later ones. When was the change? Do the parts interchange, early to late set ups? What parts can be used (if any) on the drum set up that's on there now? I know proportioning valves need changed, I'm just looking for the things at the axle to take off and replace.