I have this old merc that still runs like a top. But I never had an
owners manual. There's a plug labeled flush in the middle of the
thing. Is there a hose flush attachment I can buy to run this thing on
the stand?

Thanks in advance

Just use this fitting to flush the motor. Do not run the motor with a
hose attached there. You will burn out your water pump.

Paul

Okay, that helps a lot. That flush is more for purging water and
debris from the motor. Thanks for the advice.