I have a 2004.5 Ram 2500 4x4 that I want to change over to the 3.42 gear set. There seems to be some confusion concerning what parts I'll need for the front differential. I've called a few part supplies and have gotten conflicting reports. Randy's Ring & Pinion (www.ringpinion.com) says that I will have to use a ring gear spacer. JustDifferentials.com says that I can use a new carrier to avoid the spacer. West Coast Differentials (www.differentials.com) says that I won't need a spacer or a new carrier. I'd rather not use a spacer, as a couple of shops have said this will be weaker than what I have now.

I've sent an e-mail message to AAM asking what parts they have available for my truck to do the gear set swap. I haven't received a response from them yet. Based on other messages I've read on this board, it may be tough to get a response from them.

From what I've read on these boards, it seems that some time around MY 2006, the front differential was redesigned. Those with these newer trucks don't need a new carrier or spacer to do the gear set swap. However, for earlier trucks, either a spacer or new carrier is needed. Is there anyone with the earlier model year 4x4 trucks that has done the 3.42 gear swap? If yes, did you use a spacer or a new carrier? If you used a new carrier, where did you get the parts from?

 

Welcome to DTR!!

Where are you located?

I believe the difference is the gear manufacture. Some have thicker gears and no spacer and others use a thinner gear so you need the spacer.

 

Thanks rockcrawler, I am in Utah.

I thought that the 3.42 gears are always manufactured by AAM. What other manufacturer is making the thicker ring gear and do you know which parts supplier carries them?

 

For your truck you will need to change the carrier in the front. I have done a few of these gear sets and on the 03-05 trucks I always chage it out.

Richard

 

You have?
So how do they work out?
Brother has an 03 6spd and would like to do this.

 

raychem, what is a "fair" time to install on a 4x4 for a professional shop?

 

I have only done the swap on auto trucks and mine is auto too. I can tell you that I droped 325 rpm at 85 mph. So at 85 I used to be at 2500 rpm, now I am at about 2175. I use 85 mph since it gave me a sold 2500 rpm before the gear change which is easier to calculate. As for milage...ahh maybe .5 mpg but my truck is far from stock and mixed city hwy is about 18 to 18.5 mpg.
I know the overdrive gears are different on the manuals, IIRC they are a bit taller.

Richard

 

raychem, thanks for the info. I'm interested in where you bought your parts from. Like I said, I'm getting conflicting reports from different part suppliers. Also, could you please tell me the part number for the front carrier that you used?

 

raychem sent me a PM with the part numbers for the R&Ps and the new carrier. Here they are (these are AAM part numbers):

Loaded front carrier: 40013506
Front ring & pinion, 3.42: 40045288
Rear ring & pinion, 3.42: 40045439

If you have an earlier model year (2003 to about 2006), then the above parts will be what you need to do the swap.

Once I had the part numbers, I was able to convince Jeremy at Randy's Ring & Pinion (www.ringpinion.com) that a spacer was not needed and the swap could be done with a new carrier. Here are the prices he quoted me:

Rear R&P: $420.52
Front R&P: $266.27
Front loaded carrier: $265.05

I found a local shop (Gaylon's Drivelines in Lehi, UT) that will do the labor for $600 so I told them to go ahead and order the parts.

Hopefully this information helps others with an earlier model truck that wants to do the gear swap.

 

Just an update on my gear swap...

The shop that is doing the work ordered the front loaded carrier (part number 40013506) from Randy's Ring & Pinion. The shop opened up the front differential and found that this new carrier will not work in my truck. The guy doing the work said that the ring gear on the new carrier is too close to the pinion gear. Rather than hold up their bay, I just told the shop to order in the spacer and use it.

I wanted to use a new carrier but ultimately I couldn't find a carrier that would work in my model year truck (04.5). Randy's Ring & Pinion says that they haven't had any problems with the spacers so I'm hoping strength won't be an issue.

Anyway, once I get my truck back, I'll post some mileage results after a few tank fulls. I keep meticulous track of my mileage for city, highway unloaded, and towing. So I should be able to give a fairly accurate change in mileage for those driving conditions.

 

Any noticeable difference yet?

 

Polaraco did this swap quite a while ago. His is an 08 truck. I'm not sure if that matters or not though...

 

The only noticeable difference is the RPM change, which is great. It will be a while before I go through a few tankfuls of diesel so that I can report on any MPG differences.

 

To get a fair comparison, I waited until I did 2 identical trips to compare the swap. The same all highway unloaded trip before the swap netted an average of 17.6 running 70. After the gear swap, it increased to 19.47. Both trips were the same exact highway, approximately 1450 miles to New Mexico and back to East Texas. First trip was gear and empty ice chest on the way out with antelope in chest on the return. Second was same gear and empty chest on way out with a bear in the chest on the return. Truck was much more of a pleasure driving with the 3.42's also. I pull moderate weight alot (tractors, horse trailers, stock trailers, hay, etc.) and does fine there also.

 

has any one done this swap on a truck with the nv5600? curies on the rps in 6th at 65, which is what i normally tow my trailer at.