That M8A is probably from the 1980's. You can contact the Factory at http://www.tohatsu.com/contact.html with the s/n and they may be able to determine the year of manufacture.
Pre 1985 and they do not have records on Tohatsu's of that era. At that time Tohatsu was distributed through NIMAC, a different company, and their records were not transfered over in the 90's.
Check the gallery at the www.tohatsu.co.jp and look for model B13B. The M8A is identical to the B13B but the engine was exported as M8 and not as B13. I own one and still works as an auxiliary on my boat. These engines were manufactured from 1974 to 1976.
