I have the 3.21 and love it paired with the 8 speed. I think the 3.92s would be a little more fun but you won't regret either way you go.

 

If you are already thinking about 3.92 then I would get it now lol. If you're like me, you would always wonder!

 

Depending on how you drive. I drive 42 miles each way all highway so the 3.21 was a no brainer for fuel mileage. If I didn't drive so much, I might have gotten the 3.92.

I did drive a 3.92 first to make sure I wouldn't regret it. There was a difference but not enough to sway my decision. Maybe in the old 6 speed there might be a bigger difference, but not with the 8 speed.

I can get 23mpg on the highway, with an average of over 20 during the summer months. It's been around 19 average in the winter.

I also have the magnaflow welded in. She flies and sounds great!

 

My 14 Sport has the 3:21s and is great for all around driving with the Hemi. My guess is that the tranny shift points are different for each rear end as a set of 3:92's would really shift quickly with my tranny's shift points.

Personally, I think it's more important to add a LSD than to worry about the rear end ratio for the type of driving you described as long as you are buying the eight speed.

I'd probably order the 3:92 if mileage isn't important but if it was on the lot and had everything else I wouldn't think twice about a 3:21, I'd buy the truck.

However, just drive one of each and see what you like.

 

I have 15 with the 8spd trans, and the 3.92 I love it. Still in the break in period so
Im not sure about the mpg's yet. So Far around 19 with plenty of in town driven

 

If you are going to mod your truck (bigger tires, lift etc) then get the 3.92 But whichever you choose, definitely get the limited slip option.

 

I with BobS...if it's on the lot with the options you want I wouldn't be too concerned about the gears.
My 2015 2wd standard cab Hemi with 6spd 3.21's goes pretty good. I wanted the column shifter vs knob(but that's another thread). I don't tow or haul either.
As an everyday driver the drive train config suits my 75/25 city/highway commute and still gets decent gas mileage.

 

I with BobS...if it's on the lot with the options you want I wouldn't be too concerned about the gears.
My 2015 2wd standard cab Hemi with 6spd 3.21's goes pretty good. I wanted the column shifter vs knob(but that's another thread). I don't tow or haul either.

Same here, it was a nightmare trying to locate a crewcab with the 6 speed. Even with 3.21 rear end the truck hauls butt. I guess not having that extra 500 lbs of weight from all the gizmos really helps to offset whatever speed gains that the 8 speed+3.92 can get you.

In addition to have the last of the 1500s with a column shifter, watching that tach hovering at some a nice relaxed RPM at 70mph is just beautiful.

 

I have the 3.21 rear end and often have a payload of about 900-1000 pounds (ATV, generator, camping gear, clothes, etc). I have never once wished I had the 3.92 gearing.
I can get 19mpg (calculated) hauling 900 pounds and traveling 65 mph and have plenty of power.

 

3.92 all the freaking way, ALWAYS get the most aggressive gears you can from the factory. The hemi loves having numerically higher gears to propel it into the 4000 rpm range so the 8 speed can keep it there. Plus the burnouts are always nice.

 

I haven't driven a truck with the 3.21/8 speed combo, so I may be basing my opinion off of out-dated reasoning, but I really can't see any reason NOT to get the 3.92. As far as my pick up trucks go, I've always wanted to get the most performance and options I can afford. The only scenario I could see going with the 3.21 is if I found a truck that had every option and feature I wanted besides the gearing. Then perhaps I'd settle. To me, the mpg difference between the two doesn't seem to sway my decision at all, but I also certainly did not buy this truck for stellar fuel economy lol.

 

short and sweet, 3:92's

 

If you're not towing get the 3.21's.

Even if you were towing and wanted the extra gearing you could downshift.

The only difference I think you'll notice between the 3.21's and the 3.92's is your first and final gear with the 8 speed transmission.

Considering how short the 1st gear is anyway, it's not much of a change.

 

If it's a choice - 3.92's all the way. You won't regret it, but your tires might!

 

I think the 3.92s would give you better responsiveness if you find yourself in town or going up into the mountains a lot. But if it were me and it was mostly hwy, and mpg is your primary concern, get the 3.21s. Then if you need more responsiveness out of the 3.21s occasionally, you can hit the tow/haul button. Works for me.

 

If you aren't towing then 3.92s are completely unnecessary. The low gearing of the 8 speed transmission gives a truck with 3.21s a lower final drive ratio than one with the 6 speed and 3.92s, and its actually a greater difference than that between a 6 speed 3.92 truck and a 6 speed 3.21 truck.

I can spin my KO2s on dry pavement with my 3.21s and LSD, and with 8,000 lbs behind it I never felt a desire for lower gears. I think most of the guys who are hardcore about getting 3.92s have 6 speeds and/or haven't driven an 8 speed with 3.21s. Check out the first gear final drive ratos:

6 speed w/ 3.21: 9.63:1
6 speed w/ 3.92: 11.76:1
8 speed w/ 3.21: 15.12:1
8 speed w/ 3.92: 18.46:1

Yes the 3.92s will feel a tad faster, but the difference is about the same as the difference in MPGs between the ratios, which isn't much. My advice to you, especially since you aren't going to be towing, is to not worry about what gears the truck has. I'd make sure I had the LSD though.

 

Not entirely disagreeing but damn did the 5.7 8 speed with 3.92s feel strong compared to the 3.21s when I drove both back to back.

If you want speed you want the 3.92, it seemed to me that you are looking for a truck to go fast and enjoy riding hard. I personally would get the tallest possible gears right off the bat so you don't have to deal with a $3000 gear swap like I'm seriously considering doing. Basically unless you have diesel levels of TQ on hand more gear is almost always good considering the fact that the 8 speed gets to top gear and stays their easy.

Now if someone would be so kind as to adapt a 8HP90 to my bellhousing bolt pattern.....

 

3.55. Been there done that with the 3.92

 

3:55 is a good all round gear and would have been my choice but the 3:21's do work good with the 8 speed.:4-dontknow:

 

I decided on the 2014 6-speed Express Hemi with 3.92 because I wanted a more nostalgic truck one last time before those options go away. It's more like an old-timey truck-rod, and the 6-speed's shift points seem more entertaining to me because they give the exhaust note more personality. With the basic bench seat and the stalk shifter, it feels a little like the rumbling old trucks my dad used to have, just prettier and more efficient, and it'll get up and go too! =D

-JP

 

because I wanted a more nostalgic truck one last time before those options go away. It's more like an old-timey truck-rod... With the basic bench seat and the stalk shifter, it feels a little like the rumbling old trucks my dad used to have, just prettier and more efficient, and it'll get up and go too! =D

-JP

I can relate to this! I personally prefer the "old school" analogue dials vs the modern video displays with all the distracting flashing lights....YMMV

 

3.92's are totally nessasary. Go test drive them you'll see.

 

I have the 3.21 and 8 spd and i can even punch it without spinning the tires. But then again i do have a reg cab ��

 

I was disappointed when looking for my new truck..I wanted 3.92 but there were none equipped the way i wanted. I bought the exact truck i was looking for minus 3.92.
With the 3.21 i find myself chirping the tires accidentally all the time and I'm not an aggressive driver. I don't tow with the ram so i know i dont need 3.92 but i still wonder what it would be like to have that extra grunt.
Still I'm blown away by the dif. from 08 5.7 5 spd auto/3.92 and the 5.7 8 spd 3.21.
I dont think you can go wrong with the 8 speed aside from the stupid rotary dial.... I still occassionally reach for radio or fan speed knob when i want tranny!!!
Look at poll results 50/50..can't go wrong.

 

In my old Rams I had 3.55 gears and in this one I have the 3.92's and it's a difference of day and night. Course my old trucks weren't Hemi's though...... Anyway I don't tow anything and I also didn't buy the truck for MPG so I absolutely LOVE the 3.92's :devil:
This said, I've never driven the newer 8 speed trucks.

 

You might not like the how your 3.92 6 speed does against the 8 speed 3.21. I wouldn't of bought this truck without the 8 speed.:smileup:

 

WTH? You have to ask? Go 3.92 and never look back. Those gears and 8 speeds is a sublime combo.

 

I just traded off a '15 1500 5.7/3.92/8spd. If I could get the truck new again, would have looked for a 3.21. I drive 80 miles daily to work and could not get over 18.5. took truck to MT on vacation with an 800lb pop up camper and got 16mpg average for the trip. My boss has 3.21 and gets 21 on long trips empty and he pulls a 16' enclosed trailer couple times a year and doesn't care about mileage.
P.S. The wife agreed a diesel would be better for me....

My .02 for what it's worth.

 

Take it from me, get the 3:92's...for 75/dollars its a no brainer. I bought a new Jeep and was talked out of the larger gears...I then did a couple of mods and wished I had the bigger gears...just go with the 3.92's...u won't regret it

 

Sure get the 3.92. But you're not comparing apples to apples with the jeep thing.my 3.21 with the 8 speed does great.