Ordering 05 1/2 ton Z71....4.10's or 3.73's??

camshaft · February 22, 2005

I am ready to order a new truck. It will be a 05 GMC 1/2 ton crew cab Z71. I have the following items that will occaisonally be towed- a 17ft fishing boat, a tent trailer....both of which I'm guessing weigh around 2500lbs loaded.

As per the build sheets effective today, the 3.73's are once again a option, along with the 4.10's and 3.42's. Although I have probably answered my own question, and will get the 4.10's, any real reason to get the 3.73's?

My driving will be about 60%city, 40%hwy.....Any idea how much of a difference in fuel economy the 4.10's will cost me.......say 10%?

I will probably be adding 285/70/17's once the original tires wear out. And it shoud be noted that in Calgary our elevation is approx 4000 ft above sea level

Is anyone here getting 20mpg on the highway w/ 4.10's....if so, I have nothing to worry then.

Sorry for all the questions, any info wud be great.

99silveradoz71 · February 22, 2005

I'd steer you toward the 3.73's. Kind of the perfect combination between towing ability and reasonable mileage. With the items you listed to tow, you wouldn't need the 4.10's.

sprintcar · February 22, 2005

My '04 2500 6.0L 4wd CC only avg 12.0 mpg... but hear that 5.3L

4wd get slightly better with same configuration. I'd go with 3.73 if you're

only towing less than 25% of time

facn8me · February 22, 2005

If you plan on any modifications at all go 4.10's especially if bigger tires are in the future.

496 CUBIC INCHES · February 22, 2005

High elevation saps some of the power from a gasser and you want bigger tires. Get the 4.10s.

mudbug660 · February 22, 2005

I would go with the 4.10 cause if you step up to 285/70r17, which would be calculated at 32.6" tall, the gear ration would be compared to a truck with 31" tires running 3.90 gears. If you got the 3.73 gears with the 285/70r17 tires it would be like having 3.54 gears and 31" tires. But it's up to you.

AG Bill 05 Z71 · February 22, 2005

I would also recommend the 4.10s for the following reasons:

The difference in RPM at 70 MPH between the 4.10 and 3.73 is about 200 RPM, (2150 RPM - 4.10 vs 1950 RPM - 3.73). The mileage difference for this 200 RPM is maybe 1 MPG.

With the 4.10s and your 4000 Ft elevation, it will be downshifting less because your RPM/torque will be higher at any speed.

Real life mileage with 4.10s is about

13-14 MPG mixed (city/highway) driving with a heavy foot, enjoying your V-8...

15-16 MPG mixed driving with a light foot

17-19 MPG on cruise control at 70 MPH

Just another note: I would also recommend the steering wheel mounted controls, it is only $125 option and you get more toys to play with including the readout of MPG and remote radio controls.

99-2door · February 22, 2005

Didn't they drop 3.73s for 2005?

I thought I read the only options were 3.42 or 4.10.

If so the decision will be easy.

Elwood 2000 · February 22, 2005

I have 3:73's and my truck had 265's on it when new. I now have 285's and when towing on the highway (my loads are light too), I wish I had my 265's back on hills. While it sounds like very little difference, it does make some.

If you are going to do occasional towing and are sure you are going to 285's in the future, go with the 4:10's now. The milage difference will be very minimal.

asilverblazer · February 22, 2005

4.10's I got 3.73's and I only tow maybe 5% of the time. I would go with 4.10's in a heartbeat. The 5.3 liter has no low end you will need the gearing so it can move its own rear from a stop even more so a load.

camshaft · February 22, 2005

Thx for the replies thus far guys.

99-2door- The 3.73's are back on the build sheet. Probably cuz so many people complained that they were not available in the earlier 2005's, but if u special order one, you have the option of the 3.73's.

I test drove one with 4.10's yesterday...and d**n, the truck really moved quite well. I guess my mind is pretty much made up. Now all I have to do is find a truck......with the other specs that I want.

I was just hoping that with the 4.10's, a cold air intake and exhaust (to come later) that i could come close to that elusive 20mpg on the hwy.

rdnkcpa · February 22, 2005

I have a 3.73 rear in my 2004 4X4 ECSB with a 5.3. I have yet to see 20 MPG. I have driven it like a granny a few times and not exceeded 65 MPH and the best I've achieved was about 19. It averages anywhere between 17.5 and 18.5.

I tow a 18.5' boat and so far it towes it without any problems. Granted I don't have to tow it more than 1 mile each way to the ramp and back. I have had it on the highway a few times with the boat and trailer and I couldn't even tell it was back there. I live near sea level and I live on the eastern shore of Maryland where it is pretty much flat.

campertime · February 23, 2005

I'm glad to here you say the 3:73's are back. I'm wondering how true it is because the chevy website has not been revised (yet?) http://www.chevrolet.com/silverado/specifications/

It still shows the 1500 Crew Cab 2WD with 5.3 and auto trans

with the 3.23 standard and 3.73 optional. The 4x4 is listed with 3.42

standard and 4.10 optional.

asilverblazer · February 23, 2005

I have a 3.73 rear in my 2004 4X4 ECSB with a 5.3. I have yet to see 20 MPG. I have driven it like a granny a few times and not exceeded 65 MPH and the best I've achieved was about 19. It averages anywhere between 17.5 and 18.5.

<{POST_SNAPBACK}>

I'm giddy to see 16 mpg with those driving habits.