12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

6 speed swap? 4:10, or 3:55?

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Old 04-12-2010, 06:48 AM
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Default 6 speed swap? 4:10, or 3:55?

I'm curious if anyone has put a 6 speed tranny in to replace the 5 speed, and what kind of trouble they ran into doing so?
Also thinking about swapping the 4:10 axle for a 3:55 axle, opinions on that also.
 
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Old 04-12-2010, 07:00 AM
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There was JUST a thread on this. From what I remember, the 5spd is geared better for street driving (so unless you tow a LOT and tow a lot of WEIGHT, the 6spd will be shifted too often). The 5spd actually has the same final drive ratio. And the 5spds are tougher and MUCH cheaper to rebuild.
 
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Old 04-12-2010, 08:49 AM
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5 spd final drive is .75
6 psd final drive is .73

All you gain is the added center gear for towing.

BOTH Driveshafts need changed or the rear shortened and the front lengthened.
Different transmission mounts.

The 6spd is a ncie adition for those who either are towing alot or are sled pullers due to its extra gear.In a 12v application they are able to be held longer in gear because of the 12v's wide powerbands than if the same transmission is used in a 24v where its short powerband causes quick shifts with them in a daily driving application.

This swap was very popular with the pullers early on to have that one added gear for pulling but New venture going out of business and the 6spds inability to stay together meant many went back to their 5spds as durability was better.

That being said,if properly taken care of and maintained correctly,the 6 psd is a worthy option however it will not be a cheap swap as they are commanding big money for the transmission only due to them being very scarce.
 
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Old 04-13-2010, 07:18 AM
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I pretty much rarely drive this truck more than a few miles to work, and am pulling a trailer everyday and usually probably pulling around 10k or more 3 to 5 times a week which was why I was considering the switch.

Also are there any opinions on switching axles?
 
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Old 04-13-2010, 07:53 AM
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the 5 spd is much cheaper to rebuild. the 4.10s will help your towing. but if your not towing more than 10000 pounds the 3.55s will be fine. my best towing truck was a 12 valve, 5 spd, 4.10s. pulled easier with less tranny problems.
 
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Old 04-13-2010, 09:31 AM
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if you tow alot of weight and dont drive it much the 4.10 would help alot for towing, and be easier on the transmission
 
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Old 04-14-2010, 07:08 AM
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That has been my thinking was leaving the 4:10 since I'm towing a bunch of weight frequently. I will still think about swapping to the 6 speed at some point, that extra gear could come in handy pulling in the mountainous area I live in.
 
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Old 04-14-2010, 08:05 AM
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Originally Posted by cawhorses
That has been my thinking was leaving the 4:10 since I'm towing a bunch of weight frequently. I will still think about swapping to the 6 speed at some point, that extra gear could come in handy pulling in the mountainous area I live in.

if you decide you want 3:55's we can trade up. id like them 4:10s
 
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Old 04-15-2010, 10:10 PM
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410s and you will be high rpms on freeway 3:54 is what i got and it will still pull anything
i started with auto and changed to 5 speed & 31" tires i can run on freeway in 4th
 
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Old 04-16-2010, 06:51 AM
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Yeah that was the reason I was considering swapping rear ends was I'm cooking along around 2k on the tach. at 65 mph, I don't need to do a 100 but sure would be nice to kick it around 70.
 
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