Hey, I'm wondering if there is a VIN or Serial # on the engine block itself to determine what year model the engine is? Or is the ECU the only difference between year models?

I'm talking about VQ35DE out of some 350z.

 

Every year there have been differences between the models, some major, some minor and cosmetic. It's a lot more than just ECU.

You can get the VIN # from several places. The usual place is the dash on the drivers side. It's also stamped onto a flat section along the back of the firewall and it's on the sticker on the door jamb of the drivers door. There is an engine serial number on the back passenger side of the block but I don't believe it's the same as the VIN #.