I have a set of Infinity Kappa 62.7i coaxials the fit in a G35 coupe's rear sidepanels. They have never been used. I replaced my component set (Infinity Kappa 60.7i) but prefer the fill from the rear stock speakers.
Please note that these are 2ohm speakers, so they are designed to be used with the factory amp or being run on a 2ohm load from your aftermarket amp.
They sell at Crutchfield.com for $149 but I am willing to sell them, shipped, for $85...