GM-GMC: truck vin number, chevy 1500, option package

Question
im looking to buy a used chevy 1500 extened cab LTZ pickup. But i have found in the listings that some of the truck posted as an LTZ  have a vin number with a Z in it and some do not is this normal? Or should an LTZ equiped truck have this designation?

Answer
to be honest the vin should designate the truck option package i do not know the letter for designation

1.800-222-1020 call that number and they can tell you better than i can. if i still had access to the vin book i could but they have it and can tell you