SPI pistons for 09' M8 question

[Dogmeat]

I ordered two SPI pistons for my 09' M8 from Dennis Kirk.

The pistons have "STG 3G" stamped on them and appear to be the same, but the rings are another story.

In one box, in the same shrink wrap, I got "85 PG11" stamped on 2 of the rings .... In another box in the same shrink wrap package I got "85 PF13" ....

Why are the rings stamped with different numbers? I guess I am sort of confused here, did they put the wrong rings in one of the boxes?

 

[firecat99]

I believe two fit the top groves and two fit the bottom. I just had a set in my 05 800 SW mod motor before selling it. But I didn't notice the numbers.

 

[Dogmeat]

How do I tell which ones are which? They both came shrink wrapped in the same packages in different piston boxes....