I have some pistons in a short block with the number stamped on all 8 top of piston, 118046,UJ. Can anyone tell me the make of the piston. I have tried a part search with that number and cant find anything?

From ChatGPT - it wants pictures uploaded to better identify it. It will soon be your best friend if you start using it.
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That marking isn’t a public catalog number, but from past experience and engine builder forums:

118046 is almost certainly a forge blank or internal part number

"UJ" is possibly UEM/KB Icon or a Diamond Pistons batch code

Could also be a custom piston, where the builder used a common forging and custom-machined the dome/dish/reliefs