i have a 99 5.2l d tht has 3.55 gears and i was wanting to put something a little lower in it say like the stock 3.92s or 4.10s in it and was wondering which would be best for towing a 20 foot camper and for everyday back and fourth to work aprox. 70 miles one way so i def. dont want to loose to much mpgs

 

Well for everyday use and occasional towing, I'd recommend the 3.92 as it doesn't hurt your gas mileage horribly. This is what I have in my rear-end. As for going up to 4.10, these are not horribly much difference than 3.92, however they will affect your gas mileage a little more than the 3.92.

How much weight will you be towing and in what kind of terrain because this makes a difference what gearing would be the best. With my 3.92 I tow a 20 ft cargo trailer that weighs in about 6,300# daily and don't have an issue with the gearing.

It is when I tow my 24 ft camper that weighs in around 7,400# that I am looking to upgrade to the 4.56 rear-end just because all my truck does is tow. These trucks can definitely take it no matter which one you choose.

To sum it up, like I said if you do tow just occasionally and go work and back and are still worried about gas mileage, I'd go ahead and suggest the 3.92, you just can't go wrong with it!

Wait for hydra to chime in, he just made the swap from 3.55 to 4.10 and I'm sure he will give his .02!

 

haha yea i read yalls thread trying to find someone who did it with 3.55s and my camper weighs in at 5,600lbs and i have a 12x5 cargo trailer that i use for hauling my bikes/lawnmowers and i live in louisiana so ****ty roads and no hills but always hot for terrain

 

also ive heard that trailer brake wiring is already installed from the factory on the d's is this true

 

IF you have the 7 pole in the back, then yes it is factory wired and it's just a simple adapter you buy from AutoZone or Advanced that you plug into the back of the brake controller and into the vehicle harness.

If you don't however (like me), you have to do it the hard way and tap into the brake harness above the brake pedal and run all the electrical and wiring yourself. Granted, it's way easier if it comes from the factory, it is all possible to do in a couple hours yourself.

The way I did it was got a 'Hopkins' brand 4 pole and 7 pole from AutoZone and tapped into the tail lights myself and linked it all together. It makes it easier and I don't have to buy an adapter to convert my 7 pole to a 4 pole.

More than likely if yours came with a hitch, it's got the towing package, and the trailer brake wiring package.

 

it dosent have the 7 pole in the rear and i didnt see towing pkg on the build sheet but it has a class lv hitch on it so i guess i get to do a little wiring fun

 

Yeah it sounds to me like the previous owner put a hitch on it. It's a nice start to get what I got, it's Hopkins brand and I got it from AutoZone and has a combination of 4 pole and 7 pole. Just plug in your current 4 plug (assuming you have one) into it and just wire to the brake controller, another ground and a 12v +connection to the fuse box or whatever.

I added my own fuse and wired it from the battery.

Here's a picture of my setup, hopefully it gives you a nice influence:

 

cool i havent looked for a 7 pin at stores yet and didnt know that they made a plug and play 7 pin were all you have to do is wire the controler that is simple 3 wires is easy i was thinking that i would have to split into my 4 pin then wire it all which would be a pain

 

Yeah, i have the same setup... only differance is i went the extra mile to mount the thing in the bumper next to the reg. plate. i wanted to give it a factory look.

 

Thank you Old_School for giving me a great idea, and I'm going to take that idea and use it on mine, GREAT CALL!


Doing this is not as easy as an oil change, but it's a lot easier than most other things. To install the brake controller, link it to positive voltage, a solid ground, and use a multi-meter to check the active brake line by the brake light controller above the brake pedal.

I got home and just looked it up, that 4/7 pole combo I was talking about and here's a link:
http://www.autozone.com/autozone/acc...er=237220_0_0_


Also, here's a "behind the scenes" look at my wiring setup, as you can see I circled the part where it just connects my 4 pole that I linked to the tail lights to the combination.



HTH