You could call a dealer or SLP to be absolutely sure, but we're talking something you could check right there on the spot and be reasonably sure. That's the reason I said the door stickers were removed because that's really the easiest way to check while looking at the car. Obviously a Camaro nut selling an SS will have supporting documentation and not tear off the door stickers, but I put it out like that for effect. Not everyone cares about Camaros the way we do.
I didn't think about the sway bar size difference, so that is a very good point. But if you're not sure at gaging size difference with the eyes, you'd need to know the measurement to be sure.
But the two things that people never seem to make sure to change on these "so-called" SS cars (I've seen 3 fakes so far with these issues), are:
1) the rear suspension "jounce bumper" shims that SLP installed. Peeking through the spokes of the rear wheels (easier to do if they're the ZR1 wheels) and see if there's an extra 1/4" thick piece of aluminum spacer in there. If they're not there, it's probably a fake.
2) Open the hood and give the rear hood seal a squeeze about 3" in on either side. If it crushes completely due to it being hollow, it's very likely that it is NOT an SS. The SS would have a "stiffener" installed inside the rear hood seal. I won't say what this stiffener is made of in case some unscrupulous people want to do a better job of faking one. Can't give away all the secrets (I learned this tidbid from Jeff Yachnin [SLP Engineer] and not many know this even exists).
Apparently, the stiffener was to give better support to the ram air hood and make it seal better. Whether it did that or not, I dunno. But it's there. Not sure of WHEN they started doing this, so I don't know if it started in 1998 model year or not. I do know it's supposed to be on all the 2002. Even though it's not in any official parts list.
There may be other trinkets of helpful info, but these two seem to escape the fakers out there.
2010 2SS/RS Auto, Sunroof, Engine Cover. Transformer Edition package.
2013 ZL1 ragtop #5478. 1 of 54 CRT M6 'verts.