I have a 1995 f250 7.3 with 4.10 gears I pull a 11000lb RV I have been thinking about changes to 3.73 for better mileage
Would the change have much effect on pulling power and what would it do to the GCVW

 

I have the same truck as you, except 4x4 and with 3.55 gearing. What do you get currently for mpg while towing and unloaded? I also have an 11,000 # rv and it manages the load ok, I have had to make some wild adjustments in the transmission and HP department, but it manages 12 mpg towing, sometimes 13 mpg.

 

Prob not worth it unless you can do the gear swap/set up yourself. The cost for someone else to do it will pay for a lot of gas.

 

Mine is a 4x2 long box XLT........I get 12+ towing and 17-18 empty at 60 - 65 Nothing special all stock..

 

That's about what you should expect from a 7.3 PSD. I really wouldn't expect 3.73s to improve your fuel economy in any meaningful way (figuring in the cost of the gears)

At 11,000 pounds, you're probably already super close the GCWR of that truck, 3.73s would probably put you overweight.

 

My 87 with 460 carbed C-6 4.10 rear gets about 2 mpg less than son's 89 460 injected C-6 with 3.73 gears. The 87 with 4.10 doesn't bog down on hills like the 3.73 does

 

Thanks for all the suggestions, guess I will stay with the 4.10s
It has been suggested that by changing to synthetic in the rear end will increase MPG, any thoughts on that and what is the best additive for cetane increase..

 

When I got my 87 I put in synthetic with an limited slip additive. Couldn't tell if mileage increased as I never drove it before putting in the syn.