which as the better gas mileage 1999 chevy tahoe or the 1999 ford expedition?

[bigfoot2385_2002]

I am in the process of buying a 1999 Chevy Tahoe, but I also have an option of getting a Expedition. I am from the Bahamas and gas prices here are $4.31 a gallon. I am trying to find out which vechile is better on gas. better yet which one is better over all.