buying a new car

I am looking to buy a new car. Probably something like a used 2500hd, diesel, crew cab, long box, decent shape and mileage and the usual fixings like cruise control, a/c, heater, and the like. Is there anyplace online where dealers etc. place what they stock so I can search what they have on hand. I am looking for an efficient and fast way to find what I am looking for. I live in a small town so I imagine that I probably can get better prices if I shop around and that this will take some time. Besides from having to call ever dealership up and giving them my specs to have them call me latter with what they have what do you gyes usually do inorder to find a good deal on a car. And another problem is that since it isn't locally I won't be able to look at it so pictures or something would be nice. Thanks.

www.cars.com

www.autotrader.com

I'm sure there are others. Google 'used cars'. Good luck!