would it be worth neutering my F450 from a 4.88 to a 4.10

Since you have an F450 you no doubt you have an S110 Dana rear end which will run you $1000-$1200 just for the gears plus installation. If you have a 4x4 then you will need to do the front. Dana 60 gears will run around $300 plus installation. You will probably end up paying around $3000+ for the change. Maybe the change will net you 2 add'l MPGs? Is it worth $3000? You'll have to do the math based on your current situation.