So did 410 come factory in your auto truck? If so it sounds like my thoughts are in line. It seems like 3.55 are a steep jump in the other direction? So I am assuming that I'm supposed to have 3.55 from the factory. I need facts.

Re: 410's or 4.30's???
 

You could get 4.10s and 3.55s in both manual and automatics. Mine has 4.10s I know other people who have 3.55s. Its all what people wanted when they bought them

oh
 

I see. Well now you guys need to help find me a 3.55 rear from 1990s model dually someone who wants to trade and I go ahead with that site donation. You guys have been very helpful. Last question has any of you had experience with both? What differences did you see?

Yep, like joebob said, it was just a factory option of which gears you wanted.

You will see a significant change in rpms with 3.55's

I'm just wandering if anyone has dealt with this and seen significant change in full mileage the rpm is obvious. It should make turbo respond better or different.

At 60 you will be about 1600. At 70 you will be just under 2000 :c:

I just replaced my 4.10 for a 3.55 and i wouldnt say it was a huge difference. With 285 tires i can run 65 at about 2000 rpm, with the 4.10 i think it was 60 at 2000. I didnt notice any difference with turbo spool, I wouldnt think it would matter except in first gear towing a heavy load. I have towed my trailer since the change with no problems. My trailer isnt real heavy. I havent calculated milege yet. Overall i like the change, better freeway speeds and a little more speed out of first gear.

Very helpful stuff. I will be towing about 8,000lbs with regularity. I have more questions and comment on this truck in the future now I have to find a rear end.

why do you have to find a new rear end?

What
 

you mean?? Do you know of aftermarket gear co, that makes them? I install gears on my drag car and the setup has to be similar to that? I would think I should be able to just find someone who's willing to swap rear ends or junk yard item? I need more Mpg's out of the truck plus easier towing, I believe the 3.55's will help a little for both. In the future I'm going to do a lot to the truck, I have good tires on it that's why bigger tires are not an option right now. 235 85's!!