ok so i want to get some gears for my Z from http://mynismo.com/products/?id=6135 and the guy there told me that he has never heard of an automatic car w/ a factory lsd and when i look up my vin it says i have lsd and i'm just wanting to know if this ring and pinion setup will work in my Z be4 i order them.

 

his knowledge is not Z specific.
The only 350Z that has an open diff is the base model and the automatic transmission is not an option on the base model. So basically any automatic 350Z has factory vLSD. Your car has LSD.