1slow01Z71

iTrader: (36)

I havent seen any gears below(numerically) 3.73 for our trucks.

As far as my truck needing more gear, when on the highway pulling a 10K 24' enclosed trailer at 75mph, it did the job alright but in my case 4.56s would be perfect since I tow heavy(up to 18K) and run 35s.

I think you will find that 33s and 4.10s will be the perfect combo for your truck. Also depends on if youre towing an open car hauler or enclosed open, you MAY be able to get away with 3.55s(if you can find them) and 33s with an open car hauler.

I realize your gear ratios are nice in the lower gears but your OD ratio is what you have to worry about. Your OD gear ratio is like my 5th gear ratio(.71), towing in 5th it pulled decent but my truck is also putting down almost 800 ft-lbs at 1800rpm(cruise rpm in 5th) the 6.0 is going to be down a good 400 ft-lbs. If my truck starts to lug the turbo spools, builds boost and carries on, obviously your truck wont benefit from that, thats why Im afraid the 3.55s will be too much for the 6.0. Throw a turbo on it, and Id say go for it.

_zebra

iTrader: (5)

good point... i completely forgot about the towing part

i don't think they offered gears that high on HD models anyway, and most likely for that reason. my statement was based solely on being unloaded. with 3 tons behind, that could get sketchy

Neil 6.0

Yukon Gear makes a 3.42 set for 10.5" 14-bolts, (I'm not certain about the carrier issue, but don't see why they would make it if it didn't fit the stock carrier...call them).
http://www.yukongear.com/Default.aspx
http://www.quickperformance.com/Products/14t-gears.htm
http://www.ringpinion.com/ProductDet...spx?ProdID=621

We had a 2500 truck with 3.42 gears, my dad special ordered it. It was a 1990 Chevy light-duty 2500 (7200gvw) ext-cab shortbed 2wd/350/4L60/3.42's (9.5" SF 14-bolt). It was a great truck, had it for 11-12 years and over 200K miles on the original drivetrain. I believe the tranny had the original fluid from the factory still in it when he sold it. It was a good highway cruiser and when towing a heavy trailer we would just put it in 3rd gear and go on down the road. And that was with the old TBI 350 with what, 200 hp/300 tq? 6.0's have a bit more than that.

I think you would probably be alright with 3.42's and stock size tires, but with 33's the 3.73 may be the way to go. Hard to say for sure without actually doing it. The 33"/3.73 combo will effectively give you a ~3.40 ratio depending what tire size you have now. The 33"/3.42 combo would be in the ~3.11 range. http://www.4lo.com/calc/geartire.htm

My brother drives alot of highway miles and was wanting to try putting 3.73's or maybe even 3.42's in his '05 2500HD (auto) but with the cost of parts/labor/tuning involved it would take a while to just break even in saved gas mileage. Might want to think about that as well.

What size tire is the father-in-law's Dodge running?

subtlez28

iTrader: (15)

Wow, thanks Neil! Here I was giving up on the idea. I asked my local rear end shop and they researched some, and only found 3.73 and 4.10s.

Now I am excited again.

My father in law's dodge has 245/70/17s I believe (30.5").

I think 3.42s w stock height tires could be the ticket. Should be like a a 1/2 ton (they run 4.8s and 5.3s w 3.42s) with a bigger engine and brakes!

Neil 6.0

Agreed. Heck, on the GMT900's there is one particular truck that you can get a 6.0 with 3.42's from the factory, the ext-cab 5.7' bed with Vortec Max package. Keep us posted if you go through with this.

BlownHD

iTrader: (2)

I would recommend getting some 265/75r16 (31.7") tires to replace the stock 245/75R16 (30.5") and going with some 3.73. I have the same truck drivetrain as you, except for the 4x4. With the stock setup I was pushing some fairly high rpms at 75-85mph highway cruising speeds. the granny gear will help you get moving if you go to the 3.42 gear set, but your going to end up in 3rd to pull up hills and that is a real annoying downshift on the interstate. I would do that a bunch with the 4.10s and 33's in the Colorado mountains here. Also I've never had a problem towing in OD some people say not to do it, but the tranny can handle it, and it is a manual so you don't have to worry about trans temps. 2500rpm is where this motor starts to pull harder, and use more gas, use some calculators to see where different tire and gear combos will put you at.

subtlez28

iTrader: (15)

Well, I just pulled my camper home (the main reason I bought the truck). It pulled nicely, I'm glad I upgraded to a bigger truck.

I pulled it down the interstate in 5th. I've always understood that to be a bad idea, applying power in overdrive. Something about it being weaker.

I think the 3.42s will be ok. They should allow me to pull in 4th (currently screaming at ~3k rpm w the 4.10s). That is the beauty of the manual, you pick the gear.

I can see this causing some issue w downshifting, but it is pretty flat around here. I can live with it if it makes the truck easier to drive (and put gas in) empty. After all it will spend more time empty or w light load than towing.

Still thinking.

The Yukon 3.42s are like $350!! And that isn't counting install kits, fluid, and labor...

Still much cheaper than a GV or US Gear unit though...

dogger

iTrader: (1)

https://www.4wdfactory.com/store/pro...Gear-Sets.html

with a manual you could use a 3.42 and be all right with it. the nv4500 shouldn't be towed with in 5th gear. this is the reason so many dodge cummins have gone through so many 5th gears and even quite a few gm's have.

Neil 6.0

Yeah, that was the deal breaker for us. When you put a pencil to it, you have to drive like 50-60 thousand miles before it starts to pay for itself in saved fuel costs. He will probably trade it in for a newer one before he would have seen much benefit from doing it.

There is another tire size you might think about running to drop some revs without spending a bunch of cash on a gear swap that may or may not have favorable results. 255/85/16, they are roughly the same tread width but are 33" tall. I suggested these to my brother a few months ago when he needed new tires, but he got a good deal on some 265's and gas was under $2 so he wasn't as concerned about fuel mileage as he was when it was $4+.

subtlez28

iTrader: (15)

I may still do it. I know the fuel savings is hard to justify. But having the 6.0 buzzing at 3000 rpm while pulling the trailer (in 4th) at 65 mph bugs me. Plus, I think it will just plain drive smoother around town (less lurching).

As for tires, I will probably go wider for the sake of handling, braking, and who am I kidding looks. I already have some H2 17"s that I intend to put on (blacked out). I'm leaning toward a 285/70/17 (32.7" tall). Though I may do something more at the 30.5" range to not lose braking power.