Need help !! Jug # doesn't match bottom end #

[Trevor58]

So the bottom end of my motor (yt 125 ) is 21y 000195 which I'm quite sure means it's 1983 and my frame matches but now my cylinder has 3x3 so do I have a different cylinder? I'm trying to order a piston for my trike on eBay getting a little unsure of the piston I need

[Trevor58]

I think I have a cylinder off a 1980 I'm not sure though really need help with the piston I should grab....the piston that's in it also has 3x3 on the inside of it