318 Pistons: baffled

6 of one brand, six of another....not a great sign! lol. yup: my piston from the other thread. I figured and new post was in order, since I was straying from the OP.

This thread is about the existin pistons, and mismatch of parts! I need to get my good micrometer and measure everything as accurately as possible.

Question: the 2899446 OS marking; anyone see that before? Usually the aftermarket oversized are stamped with the size .020, or whatever.