What transmission for np205 TC and a 6bt Cummins

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What transmission for np205 TC and a 6bt Cummins

Postby 2326davis@gmail.com » Sat Sep 17, 2016 8:57 pm

So after a lot of research I gave up doing a powerstroke swap. I just purchased a 6bt Cummins 12 valve out of an 89 Dodge that came along with an NP205 transfer case for my 79 Cherokee Chief build. So now all I'm missing is the transmition and I'm wondering what would be the best route to go for hauling toys and a camping trailer.

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Re: What transmission for np205 TC and a 6bt Cummins

Postby Gumby » Sun Sep 18, 2016 1:38 am

Check out a 727, from similar year HD dodge.
1984 GW 360/727/208.... 4"/ 31"
2004 CRD QC SRW 3500 4X4 (DD)
1983 "project Dubya" (long term)

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Re: What transmission for np205 TC and a 6bt Cummins

Postby Pablo » Sun Sep 18, 2016 4:17 pm

While this was done factory, the 727 was a bad idea behind a 6bt. They don't hold up to stock power, let alone power mods. Gear ratios stink for a diesel with no overdrive. Do you want an auto or manual?

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Re: What transmission for np205 TC and a 6bt Cummins

Postby tedlovesjeeps71 » Sun Sep 18, 2016 4:55 pm

Towing? Go manual with OD. NV4500. 5600 is a 6 speed but not really much gain in gearing and its much bigger/heavier. And while the 205 is stout, don't shy away from the chain drives. Any aluminum t-case that came behind a Cummins is fine. Plus it's lighter and can be clocked better than a 205.

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Re: What transmission for np205 TC and a 6bt Cummins

Postby Resbum » Fri Jan 06, 2017 8:24 am

I ended up going with the stock offered 47RH between my Cummins 6BT and twin-sticked NP205. However, it was the single most expensive part of my build to get it strong enough to be trustworthy. The 47RH is non-computer push-button O/D and TC lock-up. When Dodge went to the 47RE (1996?, E for electronic) the O/D and TC lock-up became tied to a computer.

After doing a bunch of research of parts and mods for the 47RH, and reading real world results from people using it, I decided to build one up. A lot of the parts I put into mine are surviving in the 1/4 mile drag trucks. Theoretically, my 47RH should be good for somewhere around 1,100ft/lbs of torque.

It just costs around $4,000 to get there. This included buying the donor 47RH, parts, and the labor of an experienced shop. As I said, it turned out to be the single most expensive part of my build, so far.

However, if a person is keeping a 6BT in stock form that much work and money aren't really necessary. The number one BIGGEST thing that is mandatory to any 47RH is to replace the stock flexplate. They were too flexible and transmitted some really bad stresses into the tranny.

If I remember right, it's pretty much agreed that the flexplate is the number one biggest killer of the 47R? transmissions.

I'm not saying this is the best way to go by any means, but the 47RH is a good option if the negatives are accounted for.

Originally Posted by Resbum
"What year is my truck?... Which part?" Build thread- viewtopic.php?f=36&t=1651&p=18290#p18290

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