ive heard that 4.56s need new larger carriers for them while the 4.10s will fit in the stock one.
im not completely sure but someone will correct me

 

They make special thick gears, so you don't have to replace the carrier.

 

Here's my opinion on this for what it is worth, and from my own experience. Keep in mind that my truck has a 5.2 and an auto trans. The 5.2 is not exactly stock though either.

I started out with a 3" lift with 285's and 4.10's. It was an awesome combo. Then, I went to 35" tires figuring that 4.10's would still be fine. It was aweful. The truck was so bogged down all the time that just going up even a small hill or even having a head wind (i'm not exagerating here) caused the truck to downshift out of OD just to maintain the speed I wanted. It was terrible. I also got about 8-10 mpg. So then I went to 4.56's, and all that went away. The difference in performance is so noticable. Truck has power to spare even in OD. And off the line, it has no problem getting the big 35" muds up and running. MPG's improved too, I average about 10-12 now, which is not bad considering 6" lift and 35" mud tires.

So my advice to anyone thinking of getting 35's is to get the 4.56 no question. You will not regrete it. In fact, I sometime wish I had gotten 4.88's, but that is just because of how I use my truck. 4.56 if you want something close to how the truck performed of the factory floor (performance wise).

I see you all refencing the RPM calculators, but keep in mind that the real world is often different then this math. Just because the math says you will run a certain rpm at a certain speed with xyz gear and tire, doesn't mean you should base your decision on that alone. I ran close to the rpm's the calculators said, but the truck was still a dog. It has more to do with how much power you lose because of heavy tires, poor aero from the lift, and bad rolling resistance of big mud tires. That isn't built into the calculators, but is very noticable once you get those big tires on there.

Hope this helps.

 

That's only good up to 4.10. Above that, and you need a new carrier.

 

OK, thanks. Sorry for the wrong info.

edit, hold on a minute, http://www.ringpinion.com/ProductDet...px?ProdID=3312

 

I thought that the thick cut gears were specifically designed to fit the carriers designed for the the lower (numerically) gears?

Also, the chrysler 9.25 carrier will accept any ratio, up to 4.88. (lowest ratio for them that I have come across....)

 

Well at the time I did mine, you could not put in 4.56 without a new carrier. I did a thick gear when I did 4.10's but I had to change it for the 4.56.

 

I suppose there is only so much you can do for getting gears to fit. Besides, replacing the carrier is a good excuse to install some flavor of traction adding device...... If ya don't wanna spend the money on that, carriers for the 44 are dirt cheap on the used market.

 

Ok so right now I am running 285's if I go ahead and do 4.56 gears before I do the lift what would that do to mu mpg ??

 

Probably not a lot. You may see a loss of about 1 or 2 mpg..... Sure, the engine is turning higher revs for the same speed, but, it is also working a lot less to get the truck moving. Real possibility it could go the other way too...... but, don't hold your breath on that.