I am in the middle of getting a d16y7 rebuilt. I bought a new piston/ring set from ebay, was listed as oversized 75.50mm(+0.20"). I got them in the mail today and the pistons are clearly labeled 75.00mm and the rings are labeled as 75.50mm.

I thought both were supposed to match. Did this store from ebay just sell me some random setup that will probably fail on me

I had bought oversized because I was going with a fresh bore/hone, but I want to know if I'm safe with what I got or do I need to contact these guys to get me the right size pistons.

Again, this set up was supposed to be for a 75.50mm bore.

 

Yes it needs to match diameter. If you have the tools, measure the diameter of the piston on the skirt to confirm.

 

well I had just taken a ruler across the top and got 75mm.

there is a little stamp on the top of each piston that says 0.50 so maybe these are matched to the rings.

 

If its 75mm then its likely 75.5 at the bottom. However you should measure properly at the skirt. You should still confirm with the vendor to be sure.