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I have a 1991 Chevrolet 1/2 ton two wheel drive truck. It has a 5.7 with a 5 speed transmission and 3.08 gear ratio. We have a 2002 28 BHS that we purchased a month ago. (This is our first TT) We are equipped with sway control, weight distribution, and electric brakes.

The truck pulls the trailer ok until we hit a hill so I started looking for more horsepower. I have installed a Throttle Body spacer, aftermarket open element air breather, and will install a stage 1 chip this weekend. After speaking with co-workers they informed me that a gear change would benefit us much better for the money. I checked on a gear change from the 3.08 to 3.73 and the price was $600.00. Anyone have any advice?

Thanks, This site is great.
 

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jingram

600.00 is a great price. I just changed my 97 Tahoe from a 3.42 to 4.10. I will be towing a 26rs beginning May 28th (pickup day!!).Every quote I got to make the change was 800.00 without changing bearings. With new bearings 1200.00. If you have close to 100,000 miles you should go ahead and change all the bearings. I decided to do the job myself. saved about 800.00.
You will have a great benefit from changing it. A little less gas milage maybe 2 miles to the gal.
 

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Well, I hate to find out that I am not the only one who had this problem. I have a 2000 Durango with the 4.7L and we had the 3.55 gears. We pulled our 2004 28BHS about 6 times and we pulled great except on long grades and then it would shift down to second gear and it would still pull excellent however it was putting alot of strain on the transmission shifting so much.

Any way this past week I replaced the 3.55 gears with the 3.90 gears. We just got it back two days ago and it is noticeably better. Gas mileage is actually the same, the reason I believe it is having the same mileage is because the tranny is able to stay in a higher gear and thus maintain the speed, thus similar rpm to reach the same speed as before. My quess would be that this will actually increase my gas mileage while towing because it will not be shifting to second and reaching such a high rpm.

Before we were getting 6 to sometimes 7 miles to the gallon, I am really hoping that I am right.

Any way to conclude difinetely change the gears if you have done okay with the gear you have know then going to the 3.73 gears would be a huge difference. It costed me $600.00 for the gears and bearings and another $250.00 for labor. I am sure the other member who changed his own is a competent mechanic, and I would not recommend anyone doing this themselves because your setup has to be to exact tolerances or else the gears will wear prematurely and then your stuck for sure. I was a Parts Manager for a local Dodge dealership and worked very closely with the techs is how I know this. I consider myself able to tackle any job my vehicles may thro at me except that one.

Also be sure to purchase a good quality gear or else you will being hearing alot of noise while driving.

I will get back with you about the gas mileage I get towing next weekend. Anyhow good luck and safe towing.

Mike
 

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I have to agree that $600. dollars in a great price. I just had mine changed and it run $900.00 to go from 3:42 to 4:10 but this also included putting in the limited slip unit. If your's already has it installed that could explain the price. They also told me that there is a 500 mile break-in period before I could tow anything. You may want to check and see if you will have the same. Krk
 

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jingram said:
I checked on a gear change from the 3.08 to 3.73 and the price was $600.00. Anyone have any advice?
Is a 4.10 an option? If it is, it may well be worth considering. I sure find my 4.10 has a lot of power when towing. I'd considered the lower 3.73 but I don't regret the 4.10 now at all. The gas mileage difference between the two isn't that significant and the power sure makes going up hills easier.
 

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Discussion Starter · #6 ·
To change to the 4.10 I would need a new carrier. That is where more money would be a factor. I had considered a 4.10 but due to having to replace the carrier (more money) I decided against it. The 3.73 is a reliable gear and can be put in the existing carrier.
 

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Ditto on going with the 4.10 gears. The 28BHS is a big trailer to tow with a 1/2 ton truck. I can't believe your doing it now with 3.08's
You will be forced to tow with a big smile if you go 4.10.

I paid $1000 for a completely new Eaton posi unit, new ring & pinion gears, and all new bearings...installed. If you deduct the cost of the posi unit ($350), and the bearings ($100), then yes, you should easily be able to get it done for $600. I would highly reccomend changing all the bearings though on a truck that old.

Be sure that when they do it that they flush out the whole system (pumpkin and axel tubes) thoroughly, and refill with Mobil 1 75-90 synthetic fluid.

You will love this modification as it is going to give you BIG bang for the buck
 

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The 3.08 to 3.73 swap is a pretty big upgrade. I would be very surprised if you didn't notice a rather large difference in towing.

If jumping to the 4.10 requires a new carrier then I'd stick to the 3.73. But regardless of what you opt to do you might want to consider using synthetic gear fluid after all the work is done.
 

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aplvlykat,
tell me a little about your gear swap.
Do the 4.10's fit into a 3.42 rear end?
Did you do the front also? 4x4
How much did the non towing mileage suffer.

I have been considering 3.73's but not 4.10's. I have 4wd so I need to do front and rear but haven't checked prices yet.

Dan
 

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My Brother in law is getting his 99 K2500 4WD Burb done on Monday. He tows a 26RS and is currently running on 3.73's and going to 4.10's. To do the front and rear ring & pinions and all new bearings they are charging him $1200.
 

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Hi dan, I had my choice, I could have let the open gears( non-limited slip) and just changed the ring and pimion, about $450 or change the whole assy. which I did about $900. From what the tech was telling me they made major changes in the newer body style rear ends. He said they were correcting a problem with the carrier bearings and axels. also I asked if there was any thing I could do to beef it up and he told me that all the interior parts are the same as the 3/4 ton so no need to. For the 1999 model I think you would have to check with the shop. As far as mpg I did notice a little drop but not much, the get up a go really make up for it, what a big difference. Kirk
 

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Dan, no mine is two wheel drive so I got off easy, somewhat. Kirk
 
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