It is so easy to tell. In the trunk there is a sticker that has the options codes listed. If G85 is among them, you have LSD. There is also a plate on the trans that you can see (mostly) from under the hood. If it is LSD, it will say LSD.

Just for the record, I have an 07 with heated seats. I do have LSD.

 

Going by that ^^ I am LSD-less. Oh well.

 

ya...i have a 2.2...so obviously no lsd...and blew my diff.....by spinning the tires got replaced under warr though