So Bought my First Gen about 6 months ago now, went through more than one ecm. Turns out the truck was actually a manual when it was new and the fella who swapped the trans mission did a really low quality job. So I have been looking all over the internet to try to figure out if it would be a possibility to put a manual 6 speed from 03 into the truck. Haven't really been able to find anything so maybe someone on here has the answers. I know it will probably be a pain but at least if someone knows more about fitment that I do and what parts I will need to get extra to make the newer trans run behind my 93 12valve it would be awesome.

 

Welcome to DTR.

Running an auto PCM in a manual truck would work fine.
Running a manual PCM in an auto truck would work fine other than you would have no O/D or lock up IIRC.

So if you are going through more than one PCM in 6 months, you might have other issues.

Swapping in a 6 speed will be more work than installing a 5 speed. The 1st gen trucks came from the factory with a Getrag 5 speed, which I like to use on my 1st gens.

To get you a part list and some info. to make this swap happen, my first question would be ....2wd or 4x4?

 

I believe the 6 spd from a cummins truck was a G56? Do some searches using that and you should find a couple, lots of extra work to get a 6 spd to fit, better off with the G360 as Oliver said, or the other very common swap of a NV4500 5spd.

 

Either a G56 or NV5600. Depending on the year of the donor.

You'll need the correct transmission adapter, with flywheel and clutch and starter

The correct spline NP205

A clutch pedal and slave cylinder assembly

Lots of adjustment to the cab firewall to floor seam weld to clear the 6spd assembly

And I think you will need different length driveshafts

I have researched this topic a dozen times over. And all it takes is money and time.

Check out this thread on CumminsForum
https://www.cumminsforum.com/threads...d-pics.518829/

 

Problem with NV5600 is that there is no aftermarket support for rebuild kits or other failure prone components. And from all the posts I've seen the odds of getting a decent unit that doesn't have some major issue once torn down seems to be very tough indeed. Better off IMO to go with the NV4500, tons of rebuild kits and parts available and the swap has been done 1000's of times with a very good track record. I have never researched it but I believe the G56 at least has some aftermarket support.

Yes the gear split between 3 and 4 on the NV4500 is large and can suck but it is nothing a 3200 spring, a smaller exhaust housing on the turbo (12/14cm) and being aware of your vehicles situation is with grades, load and speed. I've got at least 250K km's operating my NV4500, as 2wd and 4wd, and pulling lots of heavy loads through the mountains and it has held up well.

 

The G360 and NV4500 (similar ratios) are going to be a very similar driving experience except for the shifter throw. If you want something with closer ratio steppings, you need to get into a different animal like a newer dodge 6spd, or adapt a ZF5 from an older ford diesel. The diesel pickup 6 speeds command too much money (IMHO).

There are also MDT transmissions with good ratio steps, but much more work involved in choosing and fitting. Although, if you can get your ducks in a row for that (and make some compromises to the 'original' aspect of your ride) I think it has the potential for a better end-result.

 

I am committed to doing the getrag 5 speed swap on mine, soon as I can. Screw this auto crap.