Im debating on switching the gears in my truck.
I do a lot of highway driving (180mi) from school to home almost all hwy 70.
Right now my truck does fine when im crusing at 70mph in IL getting about 16.8mpg (acct my gryphon), BUT when I get into MO on my way to school and start running 75 my truck has to unlock the converting going up a lot of hills and fuel milage drops to probably 13.5-14 mpg

So what type of milage are you guys getting on the highway with the 4.56's I dont care about around town, my milage already sucks there.

Just trying to decided if I need to spend the 2K on gears or just but a Lightning blower on it haha

 

Do both lol! I'm running 38's with 4.56 Gears and it does just fine. I was going to run 4.88's but I wanted a little more highway speed, if i had an extra two grand I would put in a set of 4.88's and see how much difference there is.

 

if I had that much money i would probably just buy a newer truck haha


Sorry this isnt in the other power-train section I just wanted the opinions of guys with the exact set up that I have

 

I average about 16mpg solid on the highway, but I have a 2wd, procharged 4.6. Thats with 4:56s and 315/75/16 bfg at kos.
I tend to drive about 75-80 everywhere though . If I could keep it close to 65 all day it would probably be alot better. My rpms at 60-65 are only like 1950 or something, but at 75 its getting up in the 2400 area.

And just for kicks, I would totally get the lightning blower but go intercooled too. That would be way more exciting than gears I think, not a whole lot beats forced induction.

 

HAHA! very true 31. I have so much money tied up in my truck I would hate to do it all over again on a stock truck.

 

haha yeah, I could probably piece together a L blower setup cheaper than I could do front and rear 4.56's with a tru-trac

 

What gear set-up do you have now? I got the spider gears changed in my LS and 4:56s(bearings/seals.. etc) done for like $648 but that was just the rear end.

 

3.55's

Rear Yukon gears = $303
Front Gears = $249
Since i have 133,xxx miles on it i would probably need the master instal kits with the bearings and stuff so..
Rear $240
Front $212
I would put a tru-trac in as well while was at it so + $650

Brings the total just for parts to $1600 prices from diffsonly.com

I could manage to put the blower on myself I am pretty mechanically inclined I just dont have all the precision tools for gears

 

Dang.. 3:55s are like a chick with no butt son.

 

I get 16-18 MPG on the freeway and that's with a lot of hills and steep grades. I have 315/70/17 BFG A/Ts with 4.56s and my engine RPM at 65 is about 2200. I also carry two full-size spare tires, a floor jack, and a portable tool box in the bed. With 265/70/16 highway tires and 3.55 gears, I used to get 15-16 MPG on the same drive, with only the stock spare tire.

 

 

i run from 75-80 on the highway and see anywhere from 15-18 depending where my foot is at. if im just cruising i get great mileage. when i step on it to pass or something like that it goes down of course

 

Mine is close to the same but I've rarely seen 18. Is your speedometer calibrated for the gears and tires?

 

Yes sir. changed out the speedo gear. its like 3 mph off which when you consider the realm of mpg's is not much at all. thats instant mpg not average though.

 

With 35's and 3.55's i never got 300 miles to a tank. (heavy foot) Anyway with my 4.88's and 35's i redcorded 230 on almost half a tank, but i still prolly had 40-50 miles until empty. It def better. i kno my speedo is off but i wasn't sure if that affected my odometer or not. Even so i believe i can get over 400 to a tank now maybe. oh yea, its a 30gal tank