06's did. I agree they do kind of suck in the 06's.
Just look at the size of the rear end in that think. HUGE. with that said they aren't cheap, change the fluid in it.
I am pretty sure you'll have a 48RE trans which is what everyone wants or upgrades specs to. You may have a 47re but I am pretty sure all 04 got the 48re. There were SO and HO, standard output and high output. I know there were different parts for the SO/HO and mid year changes.
If I were you I'd look for an upgraded TC. You don't need one of those 1500dollar triple disc ones either. Just a good brand heavy duty one. Then get a shift kit, clean out the valve body. There are a couple solenoids you may want to replace while you are in there. The stock TC tend to shed metal that clogs the solenoids up. If you don't have any shifting issues you can prolly just clean them out. My 05 had issues not wanting to shift in to 1st at stops. 48re with 110,000 miles on it.
Take a look at these sites, I'd give them a call and ask what they recommend
http://www.transmissionsone.com/
http://www.transmissionpartsusa.com/...ds_s/16124.htm
Also take a look here.
http://www.cumminsforum.com/forum/ge...me-04-5-a.html
The overhead is pretty close to being right if the stock tires are used and no chip. A lot of time the tires aren't factory size so the overhead and even hand calculated aren't right. I see around 16 towing and 21-22 unloaded on the highway running 70mph. Have a smarty and tow on the 30hp setting.
Here is a good programmer
http://mads-electronics.com/mads-ele...y-S-06-POD.htm
170hp gain with just a flash
upgraded TC needed