Im in the process of purchasing a 2009 Chevrolet Silverado LTZ Z71 4X4. The dealer details for the truck show 6 speed but when I ran the vin on a decoder it shows 4 Speed. How do I know exactly what Im getting. I was told I should get the 6 speed. Im not sure if I should go with the 4 or 6. Any help is much appreciated. 4 weeks of searching and my head is spinning.