Chainsaw Repair

i aksed sort of the same question on a.s.(s); a long time ago and never had much traffic.
I emailed them a while back (a few years ago) asking pretty much the same question. never heard a response from them. it was for a Husqvarna piston. mine had a '3' on the top, and so did the meteor. but the meteor also had a 'p' beside the '3'. it was a perfect fit and the saw ran perfectly fine no issues.  what i figure, and this is just a shot in the dark guess, and I hope if I'm wrong that somebody can correct me. they might be in relation to cylinder sizing like what the oem sometimes does as a match-up. maybe?