thinking about my next hotrod, the hd all have 4.10's and the reg 2500 have 3.73 or 4.10's, mostly 3.73's. i know i want at least 4.10's.

what i am wondering is if even steeper gears than 4.10's would help? i have a theory but it may be flawed, here it is. best truck to get would be a 99 2500, not HD. there are nice one's out there for under 15k, maybe as cheap as 12k. don't worry about what gears it has stock and go STEEP, like 4.56's. then swap in the hd transfer case since it is the only week link on the 2500. an added bonus is the HD transfer case is 20lbs lighter and twice as strong.

even with 4.56's i should be able to go at least 120mph in 3rd, might have to rev it higher than 6k if the truck gets really quick to stay in 3rd. i will have a rear posi and front locker, about 31" tall tires that have some tread. probably opt for the the steeper gear set when the tranny gets built(3.xx 1st).

soo? should be faster with 4.56's than 3.73 or even 4.10's right? if so then i wont worry about what gear the truck has that i buy and just plan on swaping them out.

 

4.56's with 31" tires!! Holy crap. 120 mph with it in drive, 4.56 and 31" tires. You'll be turning roughly 5900. With that set up, that sum beech will pull the wheels of the line. LOL. And here I am talking about going to 4.88's with 37" tires.

 

try some of the syclone typhoon sites they're awd see what kind of gear they're running. Only downfall is weight differance and theyre sporting a turbo, but it might give ya an idea to work off of.

 

I don't know if anyone makes a 3.xx 1st gear for a 4L80E. I thought 2.75 was the highest.

If you can get through the traps in 3rd with the 4.56's then go for it.

 

I have 4.56 with 28" tall tires on my 2000, that thing has a lot of torque. it pulls HARD.

the 4.56s would make you quicker but you also have to remember that you will be losing MPH. It really depends on the motor setup and where the powerband is, if the power band will be very high and narrow, then go as steep as you can. but if it will be a little lower and wide, take advantage of the faster MPH.

A good example is my friends 66 dodge truck. He put 4.56 gears in it and ran it, then later did 3.55s and actually ran faster. It was more gear than he needed and actually slowed him down.

with the 31s 4.56 does sound good though.

 

I can vouch for 00silverados 4.56s. Those pull like a mother ******
I got the 4.10s, they're fine for my stock ****

 

i swore i saw an add for 3.xx 1st gear set but now i can't find it. have to keep looking.

 

You guys with 4.56 and small tires. What rpm's are you turning on the highway?

 

Another thing Parish8, are you running the whole 1320 in 4wd? or just launching? You may get some drive line vibes at those speeds if you plan on running all the way through the traps.

 

On side note, what kind of mileage difference is there bewtween 31 inch tires and 4:10's and 31 inch tires and 4:56's on a 2500HD 6.0L?

Thanks!