Heather, I bought an 05 gmc diesel/ allison ex cab long box two months ago. I looked at 5 dealers. Three of the dealers had no knowledge of the trucks. They were all very nice people, but three did not know what an axle ratio was, the size engine, and lacked any ability to answer a question without spending five minutes looking it up or asking a manager. One really knew his stuff about Dodge, Gmc, and Fords. He even had exactly what I wanted, a Chevy diesel ext. cab long box with a manual trans. (very hard to find) but would not budge on the 30k price and it had lots of scratches on it like the owner fell asleep and drove into a bunch of small trees or a fence. He said he didn't notice the scratches when me and my wife mentioned them, but he noticed all the extras on it so we figured he was full of bs. I ended up buying from the general manager of a dealer that my brother went to school with. He really knew his stuff, a fanatic with trucks, he knew EVERYTHING about all three diesels. He knew enough to keep a few long box diesels on the lot too. When a salesman says I will give you the best price I can and beats everyone elses price ,knows more than everyone else and says I think this truck is your best bet but if you want me to order a new truck, any option I will get it for you unless they refuse to offer it at the plant. (He knew most all the prices of every extra without even looking it up in the book.) People like this are hard to find. So I bought the used one cause we figured a new one somewhat stripped would be 26 hundred more and 8 weeks to get. He even gave me a tour of the shop showing they service what they sell and has four of the best mechanics he can find and treats them very well to keep them there. I study very hard before I buy and he had everyone beat. I hope this helps you. I think in a nutshell HONESTY, KNOWLEDGE, and PRICE is what a person needs to sell cars. The dealer was 5 corners GMC in Cedarburg, Wisconsin and would recommend him to anyone.