78 Anniversary Edt. L82 #'s matching question

[RockSter]

I'm doing an engine swap soon and want to find out if the existing engine is factory or not. Only had the car since last summer. How can I find out if it is or not?

Thanks in advance.[emoji3]

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[bill81vette]

If you look on the engine block,on the passenger side,
under the A/C unit there is a number stamped on a boss.
the number will match the last 5 #s of the vin#
if you still cant find it ill take a pic of mine where it should be