I'm just wondering why these conversions are different than the ones from the junkyard. They use different rear axles-like the junkyard, rear brake drums-like the junkyard, but they offer new front rotors that will replace the stock 4 lug front rotors. How can you go about doing this on your own, like going down to autozone and getting these 5 lug rotors yourself? It seems a lot easier than getting the entire spindle assembly. Any info is appreciated.