Odd casting numbers

MoparMike1974 said

Easy enough to prove if its a 360. Look at the curved part of the oil pan. Its larger on the 360 because of the larger mains.

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Actually the 360 has a smaller curve on the back of the pan, the 318/340 curve of the pan would be similar size front/rear.
Look at the harmonic balancer and see if it is "externally" balanced.