So I have been readin the threads on different topics and MPH to RPM comparisons come up quite often. I'm trying to figure out what ratio I have in my 2wd. The VIN says it is a 3.73, but I have my doubts... I checked this morning on my highway drive at different speeds and this is what I came up with... (as close to the actual RPM as I can see in the wee hours of the morning).

60mph = 1950
65mph = 2075
70mph = 2250

Now doesnt that seem high to ya'll??

 

Looks like my 3.73s.

 

man if ur not towing alot, i would get some bigger tires to claim that truck down

 

The 6spd trucks in '06 only came with 3.73's due to the G56's stout .79 OD.

MikeyB

 

Yeah I forgot to add that I was on 245's. They are about 10K from being used up, and with winter time finally getting here- I'll be taking the truck more and the motorcycle less... I am definitly going to at least 285/75's on the next change out....

I'm hoping that next spring Uncle Sam will give me enough money back that I can get a set of 3.43's to drop in and pull the rpm's down even farther...

 

I like the 3:73's with the G56, but I liked the 3:55's with the NV5600 in my 2000 better. The 3.73's are great if you're pulling all the time, but running empty they're running too high of RPM with stock size tires. I plan on putting on 255/80's next time I need tires. The ones I have now are almost new though, so it'll be a while. I'd love to have a GearVendors overdrive unit, but I just don't think it's worth the cost.

 

Yeah, that truck would be 3.73's with the G56 before they revised the OD ratio.

I kind of like it, but I tow fairly heavy in the mountains.

 

Agreed

 

You definitely have 3.73 ratio differential. I installed a Gear Vendor's overdrive unit on the back of my manual shifted transfer case. Like you my RPMs were too high on the highway and fuel economy was lower than I wanted. Having said that the cost of the auxiliary overdrive transmission would have purchased a lot of fuel. I originally installed it during the time when diesel was at its highest price over $4.00/gallon.

Running in 6th gear (NV5600) and the electrically engaged overdrive on, my RPM is about 2050 at 70 with stock wheels and tires. Since you have a 2 WD pickup there is no disadvantage of the overdrive unit associated with a 4 WD truck. Gears would definitely be more cost effective, but if you start towing heavy you may wish you had the higher gear set. The Gear Vendor's overdrive gives you a 23% reduction in RPM.

L8r,...........dogger

 

How much of a MPG improvement did you see with the OD?

 

its written on the sticker in the glove box

 

Unfortunately not enough to really justify the cost. About 12% above what I was getting previous to the install. It will take many moons to pay this mod off. Having said that I will own this vehicle for many moons after it is paid off barring a severe accident.

L8r,............dogger

 

Thanks for all the info. I'm gonna go to 285/75's within the next few months, so i know that'll help out. And Hopefully drop in a set of 3.42 gears next spring (pocketbook willing of course)... I've got a good idea for an OD unit-- but that's another thread!! ;-)