RLM 73 or one of the 80s would be a most unlikely propeller colour.
When some colours including RLM 70 were discontinued as camouflage colours RLM 70 was specifically retained for propellers. The replacement colours (RLM 81,82,83) were not supposed to be used in this application,nor were they.
As Crimea River says,go with RLM 70 "schwarzgrun" for the propeller.