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Discussion Starter #1
On my 2500Hd, 2 wd, 6.0. I have the 4:10 rearend.
What is the relationships between 4:10 and 3:73?
Does the 4:10 have more power simple because it keeps the rpms higher?
I actually don't need the towing power, would 3:73 improve gas mileage?
Currently, at 65 mph, in 5th gear, she runs around 2400 rpms.
Is it possible to get that down to 2000 with a different rearend?
I have a friend who is a GM mechanic and I was thinking about asking him about
looking for different rearend gears.
Are there any other options that these two?
I love the truck, just drive without towing or pulling 99% of the time.
Thanks, Mark
 

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As you stated the 4.10 keeps the RPMS higher at a given speed.
You dont want to get the RPM below around 2250, if you do you'll be below the engines power band and you'll be constanly shifting between 4th and 5th gear when you cruise at 65mph.
Depending on tire size 3.73's could be used, if your running factory size tires with 3.73's you would see a mpg improvement of 3-6. Performance will be a little less, but you've got the 6.0 so what you give away in gearing you have on tap with horse power.
3.73 and 4.10 are kind of mid range multi purpose gears.
There are other options, a gear splitter or an overdrive unit would return great mpg. But their both expensive and the purchase price would take a long time to recoup from smaller gas bills.
 

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From what your discribing, you can lower your rpms. If you can't switch the rear, you can get a taller tires, next time. Your 5th gear is mean't to put you into a cruising (lower rpm, Less power needed,) Can you accelerate at 2100 rpm.? Many factors, . I have truck owners that cruise on freeway at 1700. medium size trucks. You mention, 65 mph. so you probly don't want to lower at lot, probly no lower than 350, .Doing good to do the reseach.
 

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Discussion Starter #4
Many thanks to both of ya.
Exactly what I was hoping to hear.
I definitly like the possible gain of 3 to 6 mpg.
P.S. Holy Smoke, LUV the Fleetside.
My tractors I take to shows are mid01950's (ish)
I always dreamed of putting together an older truck that would look "time frame" correct with tractors.
Your outfit is sharp!!!!!!!!!!!!!!!!!!!!!!!!!!
Would look awfully sharp pulling my 1956 Ferguson tractor around.
Some of the BIG BOYS are taking 50's and 60's Semi trucks and pulling 2 or 3 tractors to shows. SHARP>
 
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