Isnt any way to look at the outside of the engine and tell do like phantom said get them numbers off the back sometimes there caked with grease so you might spray some b-12 on it or get a small wire brush Ive had to use a mirror to see them before once you get the number it will be something like 3970010 .. thats an example thats too old to be in an 86 your will prolly be like 140-------
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Mortec
They will have the casting number Listed >