Now I'm no JohnsonRude expert, I run mostly Mercs and Yamahas, but today I bought my first Johnson, a 1973 6hp short shaft. The serial # is J373xxxx, and the 3rd and 4th digits are the only place in the number where '73' occurs. Maybe just co-incidence, but perhaps the 3rd and 4th digits represent the year of manufacture? If so, you may have a 2000 year model.