This out of a 1957 Evinrude 35 Hp Owners Manual

However you might still want to flush it
When you pull it out of the water, run it a barrel of fresh water for a while, keep a hose adding more water to the barrel so it over flows diluting the salt content..
There used to be a Flush adapter that clamped over the Water Inlet on the Exhaust Snout, it was made/marketed by a Company called Tempo. I have only seen one the last 30 yrs. You might find one on ebay.
Now, I know someone will say they use one of the Ear Muff Flush devices over a Water Inlet above the Anti-Ventilation Plate on the Port side of the Motor, I will not recommend it has caused problems.