3.15's were the factory fitment for the 2014 GT if it had the automatic transmission. I don't know if you could have ordered a 2014 GT with AT to have any different ratios. Link
. I assume that "LS" in that link means the usual T-lok limited slip differential.
'08 GT coupe, 5M, wheels, tires, pads, fluid, a few suspension mods . . . still almost stock height
'19 WRX, 6M (the "family sedan")
'01 Maxima 20AE, 5M (the spare and occasional winter driver)