Re: 1971 50 hp johnson water tube
The guide is part number 315838. It bolts to the top of the pump housing, above the water tube rubber grommet. So, where did it go? Well anyhoo, Marineengine.com has them in stock. You won't like the price, $50.80
EDIT: BTW, if I remember correctly, the guide is what keeps the grommet from blowing out.