Greetings,
Your "F" numbers are casting/part #'s for the heads, that's why the two numbers. My source says for V-8 trucks the Serial Number is on top of frame, left side near dash. Also on top of clutch housing. The Motor Number is identical to the Serial Number, so that would be your "VIN."
Hope this helps,
TG
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Luck is when Preparation meets Opportunity.