i posted a question a couple days ago about the gas mileage in my truck.. and everyone said that i should get new gears... i have an 03 hemi 4x4 with a CAI, throttle body spacer, cat back exhaust, and superchip. the truck has a levelingkit with 35s.i beleive i have 3.55s, but was wondering if i should get 4.56s or 4.11s. the only reason i question the 4.56 is that my highway RPMs will go way up, as i am at 2000 going about 75 mph. i know the around city mileage will increase, but i feel that my highway mpg will go down with the increased rpm. i cruise on the highway usually around 75-80 mph.. any opinions here? also i am a college student and cannot afford to put gears in both front and rear, but do not need the front wheel drive as i do not off road anymore. would it be ok if i left stock gearing in front and just removed the front drive shaft so no one accidentally puts it in 4 wheel drive? thanks.

 

you HAVE to do both dif's if you are doing gears.... also i would still reccomend 4.56's.... if you do mainly highway 4.10's might work.....

 

well if you take the DS out you don't have to but i'd recommend doing it and getting it all done and not having to worry about it.

 

y not just sell your 4x4 if you dont need it.... you could prolly make some money back....

 

My RPM's at 70-75 mph on the highway only went up about 300 or so when I went from 3.92's to 4.56's. I get about .5 - 1 mpg less now at that speed than when I had 3.92 gears and 33" tires, so mpg's is a very minor issue at best. I also gain about the same or maybe even a little more in town, so it about evens out, plus the performance difference is night & day.
If you are NEVER gonna need four wheel drive, you could remove the drive shaft and only do the rear, but if there is any way you could swing it, you really should do both...

 

With 37's and 4:56 i dont run high rpms on the hwy i think i cam close to 2000rpms