I am thinking of buying the 6 speed if the fuel mileage doesn't kill the deal. I recently averaged 18 mpg cruising at 75-77mph, rpm's are around 23-2400. What will my mileage and rpm's be with the 6 spd.

 

doing 75-80 on stock tires, i would expect somewhere in the 14-15 range. i can get near 20 if running @60mph, it falls off to 17-18 if i run 65-70

 

Do you have 4.10 gears? At those speeds I'm only seeing 2100 rmps with 3.73s.

 

Yeah you must have 4.10's if your seeing those rpm's. You'll see nearly the exact same rpm's at that speed with the G56. So your mpg's will be around the same. After it breaks in of course. Im sure your Quad stuff is helping alittle as well.

 

Mine is running around 2100 at those speeds also. 48re with 3.73

 

should not be much difference between a 5 or 6 speed, because the ratio is the same for 5th and 6th gear

 

Did I miss something ? Who has a 5 speed

 

I would have to agree with Boz. The truck in my sig turns about 23-2400 at 75. I know the truck was built to do that with 10K attached to it but I just dont like spinning it that fast. Mileage for 1300 miles I did last week was right at 20mpg. I think I averaged just over 63 mph for the trip (some 70-75 mph some stop & go).

 

Man, I think I have 3.73 gears, guess I need to check my truck. Where exactly can I find the gears??? I didnt see the 410 listed on my window sticker when i bought it. Looks like I will have to buy the 48re, I cant drive that slow on long road trips. Does anyone know how much the RPM's would drop with 35's???

 

I have the 48RE and bfg 315's and at 78 mph the rpms are right at 2,000. At 70 mph it is around 1700-1750. If I remember correctly the bigger tires dropped the rpms down 50-100 rpms. hope this helps.

Eli

 

yeah with my 35's and 4:10's im runnin 2k at 70 with 17.5 mpg

 

Look at the sticker on the inside of the glovebox door....should show the gear ratio.

 

Thanks for all the input guys!!! Now I will test drive both and make my decision.

 

I have an 06 with the 6spd manual with stock tires. I have about 1500 miles on it so far and I am spinning the motor at 2300rpms at about 70-75mph. I am only getting 15mpg on the highway but 16mpg in the city. Which I am hoping will change once the engine breaks in. I am contemplating 35's to better the final drive ratio. The 6spd. seems gear bound. I am almost certain that I have 3.73 gears. On the highway it feels like I should have another gear to shift into. I can easily start in 3rd with no load on the truck. Typically I have been driving 2nd to 4th to 6th with no engine bog down what so ever. Hope this helps.

 

2006 6 speed G56 with 3:73's = 2300 at 70-75 MPH

My 1997 had a 5 speed with 3:55's 2000 rpm =70-72 MPH

It is my understanding that the final drive in the 6th is a little lower than the old NV 5 speed AND the rear end went down to 3:73 so a new 6 speed with 3:73's is about the same as a "gen 2" 5 speed with 4:10's

I am NOT happy! I drop 5 MPG from 55 MPH to 70 MPH I easily got 20- MPG at 70 (with kayaks on the top of my cap) with my gen 2. I KNOW this truck would get MUCH better MPG with some real gears.

We need some one to come out with a G56 6th speed Over Drive conversion!

I would easily pay $1500 to have my 6th changed to be at 1950-2000 RPM at 75 MPH

I could do rims and tires... but then where to you put your spare. It will bump the hot exhaust at the elbow bend by the tail pipe.