and just bumped into another one
this is the Seiko SBDC033 a Blue Sumo - notice the seconds hand is chrome or polished steel, and the plot markers or indices have polished steel surrounds
and here is a SBDC069, also a blue SUMO, same eveything but the seconds hand is yellow and the plot marker surrounds are white
otherwise same blue everything, same case, same engine (6R15) etc