Johnson 150 fast strike model number not legible can't figure out year

[Cunliffe]

I have a johnson fast strike 150 silver star series on a 16' cobra I have not been able to figure out the year of the motor as the model number is not legible I can read the serial number this is the only SS series fast strike I have ever seen Can that help me narrow down the year? or other numbers on the engine that will give me the year?

 

[Bob_VT]

Look at the freeze plugs (welch plugs, thin metal caps - whatever you want to call them) and look for a model number stamped into them or one of them