360 piston casting numbers?

I picked up a 360 without any specs or not much informationon it. I pulled the oil pan and looked for numbers under the crown of the piston. I came up with a 11116 on one side of the wrist pin and a 030 on the opposite side of the pin.
Any idea on what pistons these could be?
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I did find some information on the numbers but they appear to be Diamond Chevy pistons? How could this be?

Thanks.