I just phoned the numbers of Five Star and OK Rig Fabricators - as stated on their websites - and reached the same receptionist.
I was connected to a party named Jason who said that OK Rig Fabricators no longer exists and so they are currently doing business under Five Star.
He talked very quickly but what I think he said was that the business name of " Fluid End Sales " is used for the Sales Dept of Five Star and that the business name of Five Star is used for the Manufacturing and Supply Dept of Five Star.