AAM gear question

[RVTRKN]

AKaiser, I finaly picked up my 3500 C&C 4X4 QC with the 3. 73 and G56 and I only have 50 miles as of now and found the RPM the same at 70 MPH as my NV5600 with the 3. 73, however I believe the tires are slightly taller by a 1/2". I'm pleasantly surprized, the performance is as good as my 04. 5 CTD even with the lower 305 HP, allthough I have not towed with it yet.

 

[AKaiser]

AKaiser, I finaly picked up my 3500 C&C 4X4 QC with the 3. 73 and G56 and I only have 50 miles as of now and found the RPM the same at 70 MPH as my NV5600 with the 3. 73, however I believe the tires are slightly taller by a 1/2". I'm pleasantly surprized, the performance is as good as my 04. 5 CTD even with the lower 305 HP, allthough I have not towed with it yet.

Based on Klenger's chart, the 70 MPH RPMs on a 4. 10 NV5600 is the speed of a 3. 73 G56. Sounds like your old truck was shipped with 4. 10s, despite what it said. BTW, about what were the RPMs at 70? The chart shows 2200 on a G56 w/stock tires, 3. 73 gears. You shouldn't notice any significant MPG difference related to the transmission gearing.

 

[RVTRKN]

70 MPH = 2100 RPM and the same as my 04. 5. I will check for 4:10 gears but I know it is 3:73.

 

[Mrudolph]

I wouldn't bet on similar numbers, MPG-wise. My 2500 has G56x3. 73s and I'm not seeing better than 17 unloaded on the Interstate. Based on a 1/2 MPG increase from taller tires (from stock 31. 6 to 33 inch), I expect to see similar results (in type, not qty, I hope) from going to 3. 42s. With the G56, the 1st gear is low enough that going to 3. 42s shouldn't cause any issues for hauling. You do, however, have to change out the front differential housing.



Got this from Swapping from 3. 73 to 3. 42 Gears - Page 4



To convert Chrysler (Dodge Ram) to 3. 42 ratio:



Rear



11. 5" Gear Set - 40045439 (New) - (Fits both GM and Chrysler 11. 5 Rears)



Front - A Diff Case and Diff Kit change is necessary for 2003 to 2006 models - use the following parts...



9. 25" Gear Set (New) - 40045288 - (used in 2007 and up)



9. 25" Diff Case (New) - 40028204 - (used in 2007 and up)



9. 25" Diff Kit (New) - 74042462 - (used in 2007 and up)

you may want to check these part numbers, AAM says the 3. 42 for the G56 won't be available until late May or early June as of this morning.

 

[birddog]

3.42's vs. 3.73

I don't think the 3. 42 would make a dog out of the truck it would put your g56 6th gear rpm's right in line with the nv5600 and I haven't heard to many people if say that there truck is dog in that situation and that they want more rpms