Are all 06 2500 srw auto 3:73 with 4:10 opt. or were they all 4:10 standard. What kind of rpms are you all spinning with an auto 4:10 in a srw at 70 mph. My dually is at about 2200 with a 6spd . Im considering a laramie h model but travel a lot and want good mpg #s thanks

 

Towing Heavy most of the time get the 4.10's!! Highway driving mostly and wanting the better MPG's get the 3.73's!!

 

With the NV 6-speed and 4.10's, my RPM is about 2500 at 75MPH.
A G56 will be alittle higher (RPM that is)...Disregard, I see you were asking about an auto

 

my last truck had 4:10s and i put 3:73s in 1000.00 and some time was much better on open road . that was also a 6 spd though . Is an auto the same final drive ratio or higher than 6spd . i tow a couple times a month 6 to 15K. problem is this is prob. the last o6 laramie around and it has 4:10.

 

Seems like my mpg is best below 2100

 

I don't know about the final drive on the auto, but I think the final drive on the G56 is lower.

 

At 70mph, I am at about 2200RPMs with my stock 265s...I have seen a bunch of folks saying that if you have an auto with 3.73s you will be more around 1900RPMs at 70, so I am assuming that I have 4.10s which is fine with me...I wish that, other than the purchase sheet which I didn't and never had any intentions of keeping, there was another way to tell...I know on a lot of older vehicles, the ratio was written on the pumpkin, reckon I'll go and check that out...

Derek

 

I guess for those days when you want to drop the hammer the 4:10 are going to be on the low side . the 4:10s in my old truck were not to bad but it was better at 75or 80 with 3:73 I still am interested to find out if the auto is geared higher on final drive.

 

I have 4.10s and at 70 it drops just below 2000rpm. At 75-80 it sits around 2300 I think.
Overall it's not bad. I still average 14mpg all round so far with only 6900 miles on it.

 

http://www.f-body.org/gears/

For those interested look at this site,,, you can see all different speeds with different tires and gears and see what ratio each gear is

 

The Auto has a lower numerically (Higer Gearing) for the final drive ratio! The Auto with 4.10's is like the G56 Manual with 3.73's!! Remember that you CANNOT get the G56 with 4.10's unless you have the Cab and Chassie! 4.10's with the Auto will turn 2200 RPM at 70!

 

If i go with the 4:10s i could put a taller tire on in when replacing. Dont want to loss the weight rating of an E . can you just go taller not wider .

 

I am pretty happy with 3:73s with 6spd. The 4:10s were to low unless you were towing over 15k. If your saying that the autos run a 4:10 the same as a 6spd runs 3:73s i would prob ok with the 4:10. the 3:73s are about 2000 at 70 in 6spd. much over 2100 at 70 would not be acceptable.