I remember when my Drake differential cover looked that pretty and new. Unfortunately the finish on it is impossible to clean and dirt sticks to it. Also the girdle bolts will seep fluid unless you put sealant on the threads. I didn't want to remove the cover again so I just backed the girdle bolts out as far as they would go, wiped thread sealant on the threads and ran them back in.
Your picture reminds me that I need to paint my axle as well.