u can check online for the radiator size/difference via aftermarket manufacturers...
http://www.nissaninfiniticlub....iator
"The radiator we carry for your car is the number 46, but ours is a high efficient core basically takes the place of a 2 row. Our radiator is $89 with shipping and lifetime warranty."
ha, the sales guy doesn't know what he's talking about; 2 rows are betta, just d/t the fact that it'll hold more coolant....
the only difference i saw w/ aftermarkets vs. oem's:full metal casting & usually painted gloss black <for rust prevention on the outside?>, but not aluminum

<@ least there'll be no leak between the al n plastic tank>
side note: i heard redline's watter wetter is a good addition to your coolin system