360 Block ID

While putting on the oil pan on the 5.9 Magnum, I noticed on the old engine it has the center bolt hole for the later trans. Now it makes wonder what is. Theres no mounting holes for the crank trigger.
The numbers on front of the block is: 3W 36R 4267
The casting number is: 9418496-3-360 not sure on the first digit.
Any ideas.

Thanks OG

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