I found in storage in the family barn a Kiekhaefer Mercury Mark 5- 5hp twin- serial number is 767487- I was told that after 1949, Kiekhaefer Corp. added the top lever bush button neutral clutch feature, which this motor has- can anyone date the aprox. year it was made in Fon Du Lac-- I may have it restored- it is currently missing the lower green cowling, and it also needs a new rubber grip on the tiller handle- good compression and spark on both plugs- Thank you