How Can I Tell If Oem Style Rear Wings On Ebay Etc Are Really Oem Or Just Oem Knock Offs

 

The wing should have a stamping on the underside with the nissan logo. Also, often times there are part codes etc...
Imitation wings will not get into this type of detail.
Also, per your other thread, about install, these come brand new with a template for the install. If you purchased it used, you will have to line up the wing and do measurements etc... Without a template, it's a tedious install, just gotta do a lot of measurements etc...
I would scan or send you a copy of the template if I had one here. If i come accross one, i'll send it to you.