I was always told to look for the little sticker in the glove box. But when my buddy up the street bought a '06 Hemi (no factory tow) the little glove box sticker said 3.55.
So, as we were dicussing his adding an aftermarkit tow kit, and at least 3.92 gears (which he was gonna have to live without for a while as the new truck tapped his wallet) his wife carried out the window sticker which showed 3.92's in the option column.
This was while I still had my factory 3.92's, so we decided to go cruising, lock the cruise control on 65mph and compare RPM's. As he was tachingroughly what I was, (tire size difference probably made the minimal difference) we deduced he did have the 3.92's.

My uncle in NY is a retired Chrysler mechanic (retired in '05), I gave him a quick call and he said as a rule the Tow Pkg. should have included 3.92's, and every Hemi he ever saw did, but said a very small percentage of the 4.7's would come through with 3.55's. He agreed with me to some extent, in that going to 3.92's or better yet 4.10's would increase towing performance, and more specifically tranny shifting as it would keep your engine RPM'scloser to the optimal powerband. Although this would keep the tranny running cooler and cause less likelyhood of tranny problems in the future, he was more hesitant to say if your MPG's would increase significantly.

He also said that theratio should be stamped on the rear axle. Maybe this will help.
You could always take it over to 4 Wheel Parts in Dallas and they could tell you in a heartbeat.

 

You can try changing your gearing
but the real problem here
is that the 4.7V8
has lackluster fuel efficiency
....but pretty good durability.

The original 4.7 V8 was designed with gasoline was around $1 per gallon
and Dodge was getting lots of complaints about engine pinging in the 5.2/5.9 V8s so they put an aluminum cylinder head with a relatively low compression ratio. Nominal static compression ratio on a 4.7 is 9.3 but when actually measured it is usually more like 8.7 to 9

The redesign of the 4.7 V8 is now complete and the revised model will show up next model year.

 

Yeah I did a no-no lastnight and went to a dealership in the area... The choices are a 2006 1500 SLT Hemi 4x2 or a 2006 2500 SLT TRX4offroad 4x4.

Both are sub 30k -

But from my readings on this wonderful site it is apparent that the non-published gas efficiency of the 2500 and the lack of MDS on the 2500's Hemi is a dumb choice between the two... Granted with my current truck I am averaging 14-15 mpg but that shouldn't be the reason to look past a 5.7L 4x2 with MDS.

Tough choices..........

 

The 2500 is not a bad choice at all if you plan on doing a bunch of towing. I have a 1500 5.7 and get 19 on the highway and between 14 and 15 in town. The Superchip tuner helped gas mileage quite a bit,even on 91 octane performance setting. The MDS might get you another 1 mpg if you keep your speed below 65 on the interstate. The Superchip has a tow setting to help save tranny wear by increasing line pressure which gives you quicker shifts. Factory transmissions are designed to slip when shifting to give a smoother ride, somewhat like slipping the clutch in a standard tranny. The tow mode in the Superchip quickens the shift, lessening the effect of the clutch slippage. This means less slippage and longer tranny life. Something to think about...

 

Bennybone,

Let's be fair and not falsely put all of the blame on the engines
involved in this towing.

When pulling such a big trailer
the pulling vehicle is like
the bow of a ship.

The Chevy Suburban shape
is probably a better streamlined
'bow' in front of that trailer
than your Ram's shape is.

You could test this out for yourself
by timing how long it takes for the vehicle/trailer
combination to coast down from 75 mph to 45 mph.

If the Suburban and trailer take more time to coast down
that combination is better streamlined
and accounts for much of the 2 MPG difference.

 

Damnquick1 has the 3.92 gears in his, it does make a differance.

 

Looking at Dodge's site now that I may have another family member interested in a Ram instead of a new Tundra ([8D] ), I also noticed that they appear to not offer the 3.92s anymore, at least not as part of the tow package. I was hoping to be able to equip their truck just like mine - Laramie, quad cab, 4x4, 3.92s, and of course - the Hemi.

 

So far the best price I can find for a gear change is 750.00 for my 4x2... Still gonna keep searching.

Also a few of you have mentioned Overdrive. I test drove an 06 at the dealership and it had the tow/haul button in the same place as my 04 however pushing the button twice would turn Overdrive Off.

How do I do that in my 04? Again to restate I only have Standard 'D' and 'D' with Tow/haul.......

 

Was at a Dodge dealer yesterday drooling over the '07 QC 2500 CTD's,(trying to decide whether to put further mods in my truck or getting a CTD, but that's another thread) andchecked out the stickers on a few Hemi 1500's.Every one I saw with the tow pkg. had 3.92's. Funny thing is - ALL 5 or 6 with Hemi (tow pkg. or not) had 3.92's, as well as thetwo 4.7's, both with the tow pkg.). Only ones that seemed to have the 3.55 were the 4.7's w/o tow pkg. Is it that Chrysler is finally started to use common sense in these builds, or does thisone dealershipjust happen to have a GM that knows how to order?

 

Look on teh rear diff cover. there should be a tag that says what the gear ratio is. It usually is painted the same as the diff. I have a 2006 QC 4.7 2Wd. I only towed anything of weight a handfull of times it was a 23' komfort trailer and it was loaded about 6000 pounds I got about 9 MPG on the freeway to hunting. I hope that helps good luck!