[NO SLO PK]

Turn the motor upside down and look closely at the bottom side of the piston. There will be edges underneath where the piston deck contacts the skirt. If edges are sharp, then it is probably cast. If thse edges are smooth and sort of rounded, it's a forging.

Looking at your image, that notch on the face of the piston, which is used to orient the piston, is usually on cast and not forged pistons.