Old G56 vs. New G56

[Southbound]

TDR Brethren-



After reading my latest TDR (great mag) it appears that the new G56 has different gear ratios per gear vs. the old G56. As most of you know the old G56 with 3. 73 rear-ends are actually getting a 4. 10 combined ratio with the short 6th gear. I agree that when pulling its probably ideal but when empty it tends to drink a little more #2 petro. I am obviously very interested in the new G56 and was wondering if anybody has looked into this??? From the magazine it appears there are a lot "unknowns" for example if the new G56 housing would retro-fit onto a 5. 9??? Let me know if anybody knows anything on this. Thanks in advance.



Southbound

 

[BHolm]

The new and old are externally identical. There are late 2006s that have the new ratios and I think most if not all 2007 5. 9s have the new ratios.

 

[WMonroe]

My 07 with a build date of 11/06 has the old ratios. Can't complain about the mileage though as this truck gets better mpg than my 97 did.

Will

 

[CSkal]

How do you tell the difference between the new and old style G56? Is there any exterior identification (tag, casting number) on the housing that would let me know? I'm just curious since I believe that my truck is a late production vehicle, but I could be wrong.

 

[chris7694]

The new and old are externally identical. There are late 2006s that have the new ratios and I think most if not all 2007 5. 9s have the new ratios.

None of the '06 trucks have the new g56 and of the '07 5. 9L trucks it's pretty rare. Mine was built in July 06 and has the old g56. There are a couple of guys on DTR with '07 5. 9L rigs that have the new g56 but both trucks, built in Dec '06, were among the last of the 5. 9's to roll off the assembly line. Probably less than 10% of '07 5. 9L's have the new g56.

 

[BHolm]

Sorry for the bad info, I could have sworn we had a member with a late '06 that had the new ratios.



I don't think that changes the ability of someone to mate the new ratio G56 to a 5. 9 does it?

 

[SierraRam]

My 07 has the old ratios, but works great with the 37's



SR

 

[JBonpua]

The G56 AE has the taller OD. Crawl under your truck and look on your data plate. If it says AE they it has the taller OD. I have the old one so I compensated and slap some 37" tires.

 

[Regcabguy]

35's please

The G56 AE has the taller OD. Crawl under your truck and look on your data plate. If it says AE they it has the taller OD. I have the old one so I compensated and slap some 37" tires.

I've got an '07 with a build date of 11-06-06 and it's got the old G-56. I need 35's badly in order to keep up with traffic. It's going to be awhile though. I wish there was a member in San Diego area who wanted to trade for my Toyo 285-70-17 AT's.

 

[Andy Morrison]

I wonder if you could swap to the new gear???

 

[Motorhead]

The G56 AE has the taller OD. Crawl under your truck and look on your data plate. If it says AE they it has the taller OD. I have the old one so I compensated and slap some 37" tires.

The truck I bought HAS the late ratio G-56. With stock tires and 3. 73's, I turn 2k at 65mph. It was built in December, '06. When I looked at the metal tag, I couldn't find where it said "AE". Roperteacher sent me a picture and the AE is on a white stick-on lable.
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[TAbbott]

I'd be curious if it would be possible to swap a lower reverse gear into the old model G-56. And, looking at the new issue of the TDR, it seems like the new version of the G-56 could use it even more! Trying to back anything heavy without using low range is kinda difficult, especially now with the Southbend Dual Disc that doesn't like to slip much at all.

 

[WOT]

Now if only we could swap the OD to . 74 and the Reverse to 1/4 of what it is! Who really needs to back as fast as the current gearing allows?

 

[Southbound]

Gentlemen-



Thanks for all of the responses. Most of you suggested taller tires which isnt an option with a dually. I have also looked at running spacers but with the bumper weight of the trailers I pull this is not an option. Unfortunately there isnt an alternate tire size that is taller yet not wider than stock. The spacing between the tires is a big issue with the heavy weight as well. So basically the only option is 19. 5's ..... lotto pending or switching to a taller final gear. I am currently running 18. 5 mpg (hand calculated) which aint bad but it may be a tad better with a different transmission. My guess is that the new G56 isnt cost advantageous based upon fuel savings??? Guess I will wait on more information on the new G56. Keep me posted if you hear anything.



Southbound

 

[JBonpua]

The truck I bought HAS the late ratio G-56. With stock tires and 3. 73's, I turn 2k at 65mph. It was built in December, '06. When I looked at the metal tag, I couldn't find where it said "AE". Roperteacher sent me a picture and the AE is on a white stick-on lable.

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Yep that is the sticker with the AE with taller OD.

 

[Motorhead]

Southbound, From what I have heard..... yes only heard, you can buy a NEW G56 from Dodge and the price is $2500. 00 That would get you the later ratio and your old trans should be worth atleast a grand or more.

 

[RVTRKN]

I will assume you have the 3:73 rear. At 70 MPH you should run at 2050 RPM with stock tires, if its the newer G56 which is what mine has.

 

[Bernie]

What about 3.42s?

I had an 06 with the G56 that, because of change of job that gave me a company F250, I sold. I had the same rev / fuel consumption problem you had.



I contacted AAM about 3. 42s for the front and rear. At the time they were not available. Apparently, they are now available (and stock on new 6 speed trucks).



The only downside, reverse is now taller too.

 

[WOT]

There was a thread going around about that but I never saw any feedback that any G56 owners did the conversion (only an auto). Without data I am not sure it would be worth it unless you just had to replace the R&P anyway for some reason.