:( Do I need to change the gear ratio becuase I gave My LLY a 6" lift and 35's?

That depends on how much of your performance you want back. It seems like most guys around here don't feel the need to regear with 35's you lose some power but with the Dmax not many have said that it's a huge issue. I would suggest recalibrating your speedometer so you know how fast you're going and so your odometer reads correctly.

I'm on 37" BFG's and tow roughly 10,000lbs. I've considered a gear change, but went with a Hypertech to get more power. You won't have a problem on 35" tires.

I have 35", if not for the fact that 6" of lift is just not enough for me, I'd change the gears. There is to much lag, and the truck just isnt as punchy as I like it to be. I would seriously recommend, that if you are happy with the 6" lift change the gears. Round these parts, its only a 1000 change. "Needed" thats another issue, but I want every inch of power I can get. With diesel at 2.50/gallon, I dont want to waste anymore diesel than I have to.

Oh, yeah. FYI on the fuel mileage, I went from 16mpg(hwy) to 14.5....

dont worry about a gear swap unless you go bigger than 35s

What about 4X4's? It would be easy to figure out if the 2500HD was straight axle. What's the gearing procedure for the front end in these trucks?
I'm picking up my brand new 2500 LLY allison from the lift shop after a 9" 11" CST treatment and 38's. It sounds like a gear swap is in my future....

Thanks for any advice, I've learned a TON from the knowledgeable folks on this site.

The front end for IFS is a 2-piece case... Like a tranfercase.. You pull the case apart and swap out .. The case splits in half and provides for the swap..

With 38's i would regear, thats way out of the power band...

With 35's I guess you would be ok for Daily Driving..

BTW: a 9"-11" IFS is asking for trouble... NO OFFENSE but tahts show truck stuff and with D-MAX power you better watch out for breakage in the front end..


BIG:)

If you wanna run with the big dogs change the gears.

Too late now! I pick it up Tuesday night. White Motorsports in Riverside is doing the lift. They did a 6-8 RCD on my last truck....drove better than stock, ran 3:73's on 35's no sweat with a 6 litre gasser. It hurt a bit on the tow to Mesa Marin over the gravevine though. :eek: They assured me that with new front shafts, new uppers, new ball joints, altered driveshaft ETC. ETC. this one will be equally as trouble free and that in their experience, guys normally don't swap gears with the diesel..... What's the typical cost to change gears in the IFS? Probably going to end up doing it.

35's with stock 3:73's here. Tow all over no problems. Speedo is about 13% off with 35's over stock 245's

mine has 315's (35's) and i got the truck from the dealer with a the lift and tires. Im pretty sure it has the stock gears with a hypertech programer. It has tons of power i couldnt imagine how it must have been while stock!! It seems to me that a gasser would need regearing and a diesel seems pretty happy w/o.

35's here too, thought about regearing for mileage and stuff, but I figured it out I can drive the truck for close to 7 years before the cost of fuel becomes more than the cost to swap out the gears...... Unless of course I do it myself, but then I'd have to buy a couple grand in tools first too, add another 3 years to the equation.

What kind of milage are you guys seeing running 35's with 3.73, normal empty driving, and towing?