Looks like an 8hp to me. Possibly a #2680 model. If it is all original, it was one of the last years that had a steel cover over the deck and white painted X series style handlebars. Look above the spark plug on the engine and find the model and serial number and if the engine is original will tell you what year the engine was built and horse power. 1977 was the only year that had a red painted steel cover over the deck (if hasn't been painted red since). The 1976 models had a plastic cover over the deck and bicycle style handle bars. Any way, model #2680 is close enough to find parts for the mower. It was an "0" series, kinda of an in between model of the older X series and the later series "1" models.