4.10 vs 3.73 on MPG
 

I have a '94 F250 automatic with the 460 engine and it currently has the 4.10 gears on the rear axle and am looking into switching for the 3.73 gears. I don't haul often and when I do, its not much weight. I was hoping someone would have some info on how much this would improve my gas mileage.

About 10% difference in gearing. Maybe a 5% increase in gas mileage, just a guess.

From previous experience with both gear ratios you are not going to gain much if anything in MPGs. It's not worth it in the short or long term IMHO. Switch to a F150 w/5.0 if you want closer to 18-20.

sounds like a whole truck change is in order.f150 w/300-6 & 3.08's rather than a hd 460 truck with 3.73's if you don't hardly haul much.
at least go with a sterling 10.25 swap with 3.55 gearing.cheapest way and large enough difference to make it worthwhile.......maybe.you'll never get what anyone would call good fuel economy from a hd 460 truck.8-10 avg mpg.very poor.remember at these fuel prices,even 20 mpg from a truck isn't exactly much to brag about.

Thanks for the advice! My cousin had some 3.73 gears laying around that he offered me and I thought i'd get more info before I spent any time and money on this.

as what was said, if you dont haul much very often, its time to get a different truck or engine, or a whole different vehicle, such as a small car, when you are not hauling something. you got a 460, there is never going to be such a thing as good mpg. as was mentioned 300 with 3.08 gearing is what i have, you caaaannnn get 20 mpg out of her but that is strictly highway, unloaded, in the summer, and driving like a complete and total grandma. which means the time when you do get 20 mpg doesnt happen very often. if there is one variable missing like you have 500 pounds in the back, or you drive through one town, i have found it drops the mpg down to about 16

luckily I do have a car that gets better gas mileage that I use as my daily driver. I just got the truck for when I want to have a little fun and this truck kind of fell into my lap in great shape and low miles. I just figured if it was going to be worth it, I'd give it a shot, but now that I have some advice I think I will just leave it how it is. Thanks for the help everyone!