The requested vessel with name SEA STALLION and MMSI:503539900 and IMO:0 is temporary not in our database.
Perhaps you mean one of the following ships:

Vessel name IMO MMSI In range Destination Last report
SEA STALLION 9563433 470521000 BARAKAH__ _ + Oct 24, 2017 05:08 UTC
SEA STALLION N/A 419900460 Oct 28, 2016 01:58 UTC

Also, you may try to find the vessel in our comprehensive Vessels Database or track this ship on the map.