Improve mileage on 1995 Dodge Ram Van 3500

Can a 1500 rear end gear be installed in my van's rear end to improve gas mileage? Am getting 13 MPG on open highway

If somehow you get back to this question(June 2010) it will come down to how much money you want to spend and is it worth it.A high speed rear end would help but your looking at more than its worth unless your a gear head and can do it yourself.Just remember you can't haul or pull without messing up the the higer gear ratio rear end.Another option(the cheaper way is slowing down and using fuel additive and changing your plugs(buy four prong electrode plugs) and wires.I got 16.7 mpg and I drove 62 mph .Just remember in the future if you by another think Chevy(18-20 mpg)