On that vintage of engine, the numbers may be stamped on the cowl above the spark plug.
All we can tell without those, is that it's post-1982 [Magnetron electronic ignition fitted].
Cheers,
Gadge
"ODK Mods can explain it to you, but they can't understand it for you..."
"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."
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