Sorry to resurrect and old-ish thread, but there's at least one member of MyG37.com
who had a gallery gasket failure on a 2013 G37.
My '13 hasn't blown the gallery gasket, but my alternator just died at 92k miles. I had it towed to the dealer, since I didn't think I'd make the 24-mile drive on battery alone.
The dealership called to say they replaced the alternator, and when the started the car, they noticed transmission fluid leaking from a crack in the transmission cooler. It wasn't leaking before. I don't know if they damaged it when the removed/replaced the cooling fans during the alternator R&R, or it was just a coincidence.
How much mileage are you guys getting out of your alternators and radiator/trans cooler/condensers?