"Robert that is a Yamaha built
"Robert that is a Yamaha built (for Merc) 1985 "C" model Mariner.
You probably have to go to a Merc dealer for parts, the aftermarket (Sierra etc) may or may not have made parts for these models (most often not since they were copies of earlier Yamaha models that had been discontinued often before the Mariner model hit production and were built with "discontinued" Yamaha parts).
An impeller goes for about 58 bucks (retail) and a whole waterpump kit for about $118.
If it hasn't been done in a while, get a kit or after you replace the impeller you will be back at it in short order putting in the rest of the pieces...."