I bet the picture you are looking for is this one. There are a number of pictures like this, but it really depends on whether you want reproductions, drawings, original ads, etc.
This picture, of course, is a painting or drawing. It seems to be on a number of Coke items. I saw a metal canister with this on it recently.
The closest I have been able to come to anything like what you are looking for is prints from Jim Harrison. That was one of the last things I found on the web, and it was right in front of me on a 2000 calendar. Well, anyway, he has some nice prints along the line of what you want, but not want you want. Jim Harrison has some nice Coca-Cola paintings of this style available on his web site at www.jimharrison.com.
Anyway, I wish I could have an answer for you, but I just couldn't come up with anything. Most of what is out there are signs and posters of advertising and not art like the truck. I'm surprised there isn't more out there.
One place you might try is if you have a Garden Ridge in your area. They carry a number of posters and lots of homey things and might have that.
The thing I know for sure is the picture came from The American Cola Company site at www.americancola.com. It is on their first page. Maybe by contacting them, you might be able to find a print.