Re: 1961 18hp Water flusher
They don't make one any more. There used to be a taco shaped flusher available, but they aren't made any longer. The only way that really works is the barrel method. If your outboard is on a transom, you can even manage it in a smaller trash can, as long as the lower unit and leg are submerged in water deep enough...over the water pump and a few inches more.
The problem is the location of the water intake. It's almost impossible to get something that will work on it.
Deep bucket, kitchen sized trash can, or a barrel. That's how you do it on those.