I just bought some mirrors for an S13 240sx. How can you tell if they're real and will the 180sx one fit the 240sx? I thought when I was looking through the pictures that it had S13 stamped onto it, but I think I was looking at a different set of mirrors that had that. Well can't really change my decision now. These are the mirrors that I picked up. Also I apologize in advance if I posted this under the wrong forum.
https://page.auctions.yahoo.co.jp/jp/auction/345490425
If you scroll down you'll see the pictures they have

No clue, but those look real enough to me. Not brand new condition, but maybe new old stock. The foam around the edges looks a bit old, as does the manual that comes with them.

Buying from JP is a good start, doubtful there'd be Taiwanese knockoffs on there.

I think I paid over $200 for mine, more than a decade ago, so that's a good indicator as well.

Welcome aboard!