I have done a lot of reading and searching on here before deciding to ask this but here goes:
Rebuilding my 2003 G35 due to loss of oil pressure, noise, and smoking. Caught it before the bearings got hot and spun but they did wear into the copper.
Please keep in mind that I am on a very tight budget with this, not building a race car and may in fact sell it when done with this. I got most of the parts from Rockauto due to cost and my past good experience with their affordable parts. The pistons I ordered are DNJ part number P644, which is what their catalog calls for in the 2003-2004 G35. Upon receipt, those are a flat top piston whereas mine have valve reliefs in them. Othere than that, all other specs are identical. Going back to Rockauto's catalog, I looked up other models 2002-2005 and found a P645 piston that looks like what is in my engine. Their application info says its for a 2002 I20 with VQ-35DE and the 2005 and beyond G35 with that engine. They show those flat tops P644 are specific to the 2003-2004 G35.
My questions are:
-Is rockauto's catalog wrong
-Do I have the wrong pistons in my engine now
-Will the flat tops work
-Should I just swap them out for the P645 pistons even though they are not called for in my model and year?
-Is there something I am missing about a change in compression ratios during those model years that calls for the flat tops as a suitable replacement?

Thanks for the insight (and for not criticizing my choice of using affordable pistons)