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I ws wondering if anyone tow a Outback 28BHS with a 1999 Suburban 1500, 5.7 V8, with the 3.42 axel ratio. How does it tow?,if so. Can anyone tell me how much my tow rating will increase with a gear swap to a 4.10 differential? I can't seem to find any actual numbers for the 1999. They give it for the 3.73, but not for the 4.10.
 

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As you can see I have this setup. If you are not towing in the mountains you may?? get by. I got the 25RSS because of the weight was all I wanted to pull with this truck. Your truck will pull 5000lbs. if it's a 4wd, 5500lbs. if 2wd. You MUST have synthetic trans fluid for better cooling, and synthetic gear lube front and back. I have an aluminum finned trans pan with 4 extra qts. of fluid and a second trans cooler with a fan. I can keep my trans temps under 190 in the pan. I have considered the gear change also. I have the 4wd so it will need both front and back diffs changed. I am in the midwest so I have some hills but no mountains and can get by for now. My next mod is going to be a Heavy Duty transmission rebuild as the 4l60e is the weak point for this drive train if used for towing (althought my last suburban made 177000 before I traded.) The Swap to 3.73 Gears will give you 1000lbs. more of tow capacity to 6500lbs. or 6000lbs. (2wd or 4wd)
Dan
 

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Sorry I missed this thread while away last week.

First off going from 3.42 to 4.10 gears will make a VERY noticible difference in your towing experience. 3.42's are a really weak ratio and have no business in a tow vehicle (please don't flame me guys
).

As Dan said, you will gain 1000# of towing capacity going to the 3.73's. For a 1/2 ton 2WD like mine this would mean 6500# max, and 6000# if it were 4WD.

Now an interesting side note. I upgraded my stock 3.73's to an Eaton Posi with 4.10 gear ratio. So does this mean I can tow even more than 6500#? In my case the answer is no. Because I have tires 2" oversized in diameter, this eliminates the gain in ratio torque from the new unit. So I'm still rated at 6500# max. Now if I had kept the stock diameter tires then perhaps I could go above 6500#.

However, because of the low amount of load carrying capacity of my 1/2 ton Suburban I would likely use up my limit in tongue weight before I could hit my maximum trailer weight capacity.

Did I answer a question here
Sorry if I wasn't clear. Ask again if you have any other questions and I'll tell ya everything I have learned while researching mine.
 
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