Age of 90 hp yamaha with damaged identification label?

[fishingaddiction]

I have a European Yamaha 90hp Autolube 2-stroke, model 90A ETO. The identification label is in bad condition, so no letter is visible on it to give year of manufacture.
Can year of manufacture be obtained from the serial number alone which appears to be 6H1-L-492092?
Also, is there any other marking on the engine that I could use to identify year of manufacture?

Any help would be much appreciated.

[jb123]

6h1 1983- 90a/aeo/aeto