6 spd or auto, that is the question.

[Turboman]

I am thinking of getting a Megacab. I have always run 6spd for the reliability of it. I would like an auto if it will hold up. Have they improved the 48RE enough to handle the heavier loads. A friend has an 04 auto and he won't tow anything in OD and he only gets about 8mpg. Would I have to modify the auto to handle say a 14000# fiver or should I stay with the manual?

 

[67guzzler]

Maxicab? What's that?



Hmmm... . transmission Wars.



I have the G56. No troubles so far. Funny noises that's it. I had a 2004. 5 w/the 48RE and didn't like it. Too high of a stall speed for me. Hit the accelerator and the thing pegs 2000 rpm and sits there. Almost feels like an CVT. Very bad fuel economy around town due to the high stall speed.



The 48RE has been considered a refined and robust transmission as compared to it's predecessors when used with an engine in stock form. There are tons of upgrades (torque converter and valve bodies to start) that can make it pretty much bulletproof if you decide to add more power.



The G56 mates to a dual mass flywheel that has given a bunch of people the heebie-jeebies. But nobody knows if it will be a problem or not. The transmission itself from all accounts seem to be pretty tough.



Not much help I'm afriad. Seems to be personal choice on this one.



Good luck!

 

[klenger]

It seems that with the very positive results of the 48RE that the choice is pretty much personal preference now. It used to be that the 5 or 6 speed was the defininte winner for relibiality, but with the 48RE track recored, reliability is pretty much the same for both.



I'll keep my 6 speed, thank you very much. I like having total control over gear selection and the simplicity of the manual.

 

[jwduke]

Well, when I bought my truck, I didn't want a slush box, but I got a deal I couldn't refuse!



I wanted a stick & I was worried about reliability. Well the dealer I bought mine from is a friend of mine. He told me thats what warranties are for! (We ALL know how they work, right??? LOL!) So I went with it.



Well I tow a 8600 lb. HR 5th wheel, 4 people & all of our junk. This thing works like a good (not fine) swiss watch! My next one may be a stick, but the 48RE is a real joy to drive, and with a few mods, I think it could actually be fun!



So the choice is yours... ..... But for the money, the 48RE is no sloutch!

 

[RVTRKN]

I think auto,s are for gasers. The new diesel torques ratings for all brands can destroy auto,s, even the allison trans. My work truck purchased by my employer is the 05 duramax with allison trans W/service bed. The top end power band sucks even with overdrive off. My 04. 5 NV5600 trans POV kicks its ***

 

[corprimo]

If you're going to tow, you'll want and exhaust brake, and if you have an exhaust brake, you'll want the 6 speed. You can engine brake in any gear and not worry about whether the torque convertor is locked up. I've got the PacBrake, and use it empty or towing. It helps the engine warm up faster in cold weather. I have the Auto in my '97 and had to put in a heavy duty valve body and torque convertor and mystery switch to lock up the torque convertor - pain in the butt. You get a bit of excercise with the 6 speed, but it's great to be able to put it in the gear you want when you want it, plus have braking in any gear.

 

[klenger]

For 06 trucks, the exhaust brake is no longer a transmission factor anymore. The 48RE is fully exhaust brake compatable now. As much as I like my 6 speed, we can no longer use the exhaust brake as a point in favor.

 

[corprimo]

Can you use the Exhaust brake in 1st or 2nd gears with the new Automatic? I've been in situations where I needed that (Dawson City, Yukon). Didn't dare go faster than 25-30mph and regular brakes were starting to fade. I had to bring our rig to a stop in a cloud of brake smoke, shift into low range, and decend in 3rd gear with torque convertor locked up and exhaust brake doing its thing. Brakes were smelling for a week after that. I know, I never should have pulled the 5er to the top of that mountain for the scenic view, but once we were up there, we had to come down...

 

[Ereynolds72]

When did they stop installing the NV5600 and start installing the G56?

 

[Grizzly]

I think auto,s are for gasers. The new diesel torques ratings for all brands can destroy auto,s, even the allison trans. My work truck purchased by my employer is the 05 duramax with allison trans W/service bed. The top end power band sucks even with overdrive off. My 04. 5 NV5600 trans POV kicks its ***

I have to agree with RVTRKN. There is no way you can beat a 6 speed if you have a diesel and you are going to pull a big load. Now if all you are going to haul is a load of flowers to a funeral, that's a different story.

 

[klenger]

When did they stop installing the NV5600 and start installing the G56?

Early calander year 2005 .

 

[JCleary]

I drove a G56 Megacab. I liked it a lot, except for the low final drive ratio. The truck really needs some 35" tires to bring the rpm's down at 75mph. Or some 3. 54 gears instead of the 3. 73's. You'll probably like the gearing with a 14k fiver, though.



When I buy my next truck it will be an auto with 4. 10's. I know I will BOMB away, so next time I want an auto so I can better spank ricers, vettes and mustangs at stoplights. My first two mods will happen at the same time- a tst and a fully built trans. The rest can come later.



My only complaint with a six speed is that you have to do your hunting on a roll in third gear or higher. No blasts away from a stop light in 3rd unless you have a dual disk clutch.



$5k for a built auto, or $2400 for a dual disk? I'll pay the 5 grand for the auto next time.

 

[Bertram65]

The auto tows great and will out perform a stick in any acceleration test loaded or unloaded, no boost drop when it shift gears, just smooth pulling. 99% of the towing I do is above 45mph so the TC is locked and provides some braking on downhills when in 3rd, in traffic the auto wins hands down, stop and go is bad enough emtpy I would not want to do it with 10k lbs in tow with a stick. There may have been a big advantage with the stick when the 47RE was the auto choice, but with the 48RE the choice is pretty much user preference.

 

[gonzo2]

If you are towing heavy frequently with the auto, go with the 4. 10 diffs.

 

[hasselbach]

I have had both, a 04'5 auto, and a 05 6 speed.



Both have their good and bad traits. The auto's torque converter sucks. Its a pile of crap, way too loose. But ATS, Suncoast, DTT can do wonders.



The 6 speed clutch is marginal (I've smoked mine), its a pain to shift quickly (nv5600 is very notchy, but I understand the g56 is a lot smoother).



If you are looking for stop light to stop light action, I'd go with the automatic. If you tow heavy, and want better mileage, the 6 speed. My auto would get 14. 5, yet my 6 speed returns 18 mpg.

 

[BHolm]

My '03 dually has over 90k miles worth of heavy towing under its belt. It is an HO engine, 48re, 3. 73 gears. There is NO reason to not pull in OD, that is why your friend gets 8mpg. The truck will tow all day long with an insane load on in OD, been there, done that. I am on my fourth third gen with this trans and they have been great, much better IMO than the two allisons I had.



The exhaust brake with the auto in the '06 will work in second gear. It automatically shuts off between 20-25 mph and is not meant to work in first gear because there is no convertor lock-up provision. Living in the mountains I have been using it a lot. It takes a fair amount of driver participation to get the most from it but still less than a six speed.



Keep in mind that a 14k lb fiver is getting right up to the max towing rating for the truck. There is a good chance you will be over on the pin wieght too. I would check out the weights and make sure you are not in dually country. I wouldn't worry about the trans for a second though. My dually pulls a trailer all the time, 8k empty, 15k loaded. Never misses a beat.

 

[tschwab]

TWO thumbs up on the STOCK Cummins 610 & 48RE, tows great and outpreforms my buddy's built '01 with that famous maker 5K built transmission when towing. I will stay stock (motor & transmission) with no worries, if it blows up, that is what my 7/70 powertrain is for, if the Cummins blows I have got 7/100.

 

[madduck]

Another thing to consider, as in my case, besides towing was ... . yuck... . snowplowing. So I went with the auto figuring that the constant clutch work would cook it pretty quick, besides the sore left leg.

 

[JStraw]

I use the auto for another important reason. If I'm out camping in the back country and have a heart attack or other injury, I will need the wife to drive me to the hospital and then be able to go back and get the 5'ver. She couldn't do this with a 6 speed. She could drive it empty but towing with a clutch isn't her bag of tricks.

 

[Cummins Cowboy]

saw this thread and in response to the orginal question, I have been thinking about the same thing next summer my lease is up, so I will get a new truck. the only problem is I hate the gearing in the current g56, to me they ruined the best trans and gearing combo they ever had. I don't want to cruise 70 at 2200 rpm, this is way more than the effecient range the engine should operate. it would be like my current truck going down the road at 80mph. with my setup if I approach a big hill, and only on the steepest highway grades in utah, I down shift to 5th I only do that because I want to pass most everything in sight pulling a trailer. I could leave it in 6th and be content with 60mph over the grade. this is with a truck with quite a bit less rated power than the new ones. I really really want a 6speed for my next truck, but I will not be able to handle the gearing, without getting bigger tires which I don't want to do. I am hoping at midyear they will offer a 3:55 gear in response to the problem. otherwise I just might get the auto so I don't have to worry about gearing