What the difference in evinrude 1976 115 hp model numbers? ( model # scratched off my engine)...115699d,115699g,115693d,115693g?

INTRODUCES = 1234567890. ES =1990
The last two characters of the model number (that make sense) are your year.

Rob, AQABVA71K899 does not seem to come up as a valid # for referencing engine. Check the attached links,instruction and guides, Good luck
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Outboard Engine Serial Number Year Match up
Evinrude Outboard Motor Model Numbers
EVINRUDE OUTBOARD MOTOR MODEL YEAR LOOKUP GUIDE 1913 1979 MASTERTECH MARINE

I found a mixture of sites for the information
one owner of a 1998 25 hp evinrude says that it is a 2 stroke with a fuel mix ratio of 50:1 as 25:1 is a bit smokey
another site says that the recommended octane fuel rating is 87 although it might run better on 91
best advice is to find an evinrude service dealer and get the right information as the later 25 hp units are etec engine which will be 4 strokes

The block plug could have the original model and serial but not that number. The E60TLCS is a 1980 60 hP

An evinrude dealer may be able to help you

check here http://shop.evinrude.com/media/document/ModelNumberReference.pdf

1978 It is in the model on an Evinrude. 6804.... 6 HP.....1978