Correct paint color for a 1970 Dart 8 3/4 axle assembly

My dad bought a new 69 Coronet R/T track pack new in 69 for my sister. I ended up with the car when she got a new 71 Duster . The Dana rear in 2 years in the R/T was solid rust as was the 4 speed and the drive shaft. If it was painted it only lasted a year.
I paint everything on cars I redo. My Demon everything will be powder coated. Who cares what they were. They are only original once. If you recoat them its only to hide and prevent the rust and then its not original anyway.