I believe they were still using the 48RE behind the diesels. All the parts to do the swap should be readily available.

 

Yes 03-07 used the 48RE, 03-05 trans is what you need though as there were some control hardware changes in 06

Honestly though going from a manual your options are so much more viable I was seriously looking into an allison 6spd swap for my 06 Cummins before I traded it off, towards the end I ran into a 68rfe for cheap on Craigslist with some issues

Both swaps that way are still pretty costly but the standalone is out there an both are better options then a 48re in my opinion unless you're looking for a race truck, 48re is the cheapest to build

 

The best transmission for towing is the NV5600 you have now. If you want an auto a built 48RE is the best option, way better than an Allison.

 

can never go wrong towing with more gears agreed ideally the nv5600 is a good towing unit but if he wants the auto conversion just aswell make informed decisions ive never had a "built" auto but any stock 4spd I absolutely hated towing with constantly shifting up and down, my 2010 was way better probably both having more power and the 6spd auto

 

The 68RFE 6 speed auto has more gears but it isn't much stronger than a stock 48RE and it is much more expensive to build, also I don't think there is a stand alone controller for the 68 so it would be difficult to make it work properly. A built 48RE behind a 5.9 with a few mods should be able to tow anything the truck can handle.

 

Actually, there is a company doing conversions, complete with trans controller, for the various diesel trucks. I was considering such a swap for my 98 2500 with the V-10.... (more gears=better fuel mileage) But, I was looking at over a grand for the adapters to bolt the trans up, and closer to 3K for a controller to run it...... not to mention all the other stuff that would need to change to install the larger trans.

 

yea thats what i ran into on the alison swap, one plus is SAE #3 housing could fit a heavy duty starter but torque converter adatper t case adapter mount brackets ect over 1000 then another 2k for ecu and harness i work at an allison certified shop all the allison needs to run a oem allison cal is a 1939 conector for tps % for me on the 68rfe swap being an 06 the converter and such would bolt up the research i could find the t case would bolt up, i dont think is 2 inches difference in length so a guy could possibly even fudge the driveline in

strenght wise your about a wash with any stock auto 48RE is the cheapest to built but i love towing with more gears and the double overdrive is sweet for mileage

 

What company!?!?

 

These guys.