I have an EJ20G from a 95 wrx wagon, gonna rebuild it shortly here. I need to identify the pistons to get a rebuild kit but I don't really know. I've heard there are markings on the case or on the tops of the pistons. I saw a bunch of markings on the case but I have no idea. Definitely no easily identifiable A or B. Engine is from Japan. Any suggestions?

Yes. Clean the area behind the oil pressure switch where the two blockhalves meet. There should be a combination of A and B (and on older engines even C). In the same area, there's also a numeric code which says something about bearing size, although that's of no use for rebuilding.

thanks, i'll give it a shot tonight

yes, found them just fine, thanks much, that was a good description, i searched before, i didn't realize the flat surface they're engraved in is low and not so noticeable, plus being very dirty it wasn't easy to find, 2a's and 2b's, thanks again