Gears??

[busta]

Okay here is a dumb question for all of you smart people. I see all this talk about what kind of gears everyone is using and all of that good stuff. Is there an easy way to tell what gears I would have on my truck. I have a 2000 GMC Sierra 1500 LS 4x4 ext cab 6' bed...any other info you might need?? Thanks

[busta]

Oh and it has the 5.3

[Kyle401]

Look in the glove box for the option code label

 

GU4 - 3.08

GU5 - 3.23

GU6 - 3.42

GT4 - 3.73

GT5 - 4.10

[busta]

I knew there was a logical answer...THANKS

[busta]

Well I found out that I have 3.73 in my truck...so here is the next question...are those good??

[trever1t]

Good for what? It's all good i usually will say!

No, really? What do you want to do with your truck? I just re-geared to 3.73 because mine was geared more for highway with 3.42 and most of my driving is inter city at like 65 mph so the lower gear ratio is better for me.

Do you tow often?

Do you long distance commute on flat roads?

Smaller #'s = taller gears= less RPM at a given speed. 3.42 in OD = 1800 rpm at 70 mph.

larger #'s = lower gears= higher rpm. 3.73 in OD = 2100 at 70 mph.

[busta]

Daily driver...highway/city driving...some hauling some light towing

[trever1t]

3.73 is what i chose! Gear change will run ya a little over $1K + the cost of a LS or locker! My 3.42's were way to tall for me so it was worth it!

[Kyle401]

IMO, the 3.73 ratio is a good balance for a truck owner who uses their vehicle for towing (less than 40%) and for unloaded commuter usage. The 3.73 ratio allows the engine to rev higher in the same gear (compared to 3.08, 3.23, 3.42) at Highway speeds which places the engine higher in the power band. This is good for towing and hauling; however unloaded fuel economy is not as good as it would be with a 3.08 gear ratio for instance. As a general rule of thumb see below.

 

3.08 - best for unloaded fuel economy, worst for towing

3.23 - better for unloaded fuel economy, better towing than 3.08

3.42 - pretty good balance between fuel economy and towing capacity

3.73 - better for towing, fair unloaded fuel economy

4.10 - best for towing, worst for unloaded fuel economy

 

I have had the 3.42 ratio in my last truck but opted for the 3.73 when I upgraded. I pull a boat during the summer which weighs in around 4500 to 5000 lbs and felt the 3.73 would give me a little better towing performance while still offering decent fuel economy when unloaded or lightly loaded. Overall, I think that the 3.73 ratio is one of the most popular among GM truck owners.

[busta]

Well I dont plan on changing any gears out...I was just curious as to what I had...Thanks for all the info

[Rammer]

IMO, the 3.73 ratio is a good balance for a truck owner who uses their vehicle for towing (less than 40%) and for unloaded commuter usage.  The 3.73 ratio allows the engine to rev higher in the same gear (compared to 3.08, 3.23, 3.42) at Highway speeds which places the engine higher in the power band.  This is good for towing and hauling; however unloaded fuel economy is not as good as it would be with a 3.08 gear ratio for instance.  As a general rule of thumb see below.

 

3.08 - best for unloaded fuel economy, worst for towing

3.23 - better for unloaded fuel economy, better towing than 3.08

3.42 - pretty good balance between fuel economy and towing capacity

3.73 - better for towing, fair unloaded fuel economy

4.10 - best for towing, worst for unloaded fuel economy

 

I have had the 3.42 ratio in my last truck but opted for the 3.73 when I upgraded.  I pull a boat during the summer which weighs in around 4500 to 5000 lbs and felt the 3.73 would give me a little better towing performance while still offering decent fuel economy when unloaded or lightly loaded.  Overall, I think that the 3.73 ratio is one of the most popular among GM truck owners.

 

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If you lived in flat country, I would agree. But here in hilly western PA. I'd bet I would get better milage with 3.73 than 3.08 any day for everyday driving. Engine RPM isn't the only thing that will effect fuel economy. Engine load will have a greater effect on your fuel economy.

[Kyle401]

If you lived in flat country, I would agree.  But here in hilly western PA.  I'd bet I would get better milage with 3.73 than 3.08 any day for everyday driving.  Engine RPM isn't the only thing that will effect fuel economy.  Engine load will have a greater effect on your fuel economy.

 

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True, results in specific conditions will vary. However, as a general rule of thumb, the above applies.

[97chevy350]

I have 3.73's in my 97 and get less than good mileage, mostly due to driving habits, but my dad went from 3.73 to 4.10 in his 99 for towing and he didnt lose any mileage at all, he actually gained a little. However, at the same time he had the computer reprogrammed and had the torque converter lock-up stiffened up a little, so that played a role.