just bought 2004 2500 larmie 4x4 auto with all the wife goodies. was built 5/04 not real sure of what engine i have want to add exhaust . i measued it and is already 4.0 inch so im lost again. new diesel owner! any other help would be great. oh whats a vent mod on my fuel tank. thanks

 

look on the drivers side of your valve cover for the sticker with all the info, there you will see the advertised hp numbers, 305 or 325 that is the only way to tell what motor ya got, but it will still only narrow down the location of your tps to 3 possibilities

 

You have a 600 engine.
1/01/2004 manufacturing switched over to 600's.

 

The vent mod raises the vent tube to the top step of the fuel tank. It allows you to completely fill your tank very quickly. Without it, the pump will click off even though you can still put 4-5 more gallons of fuel in it.

Do a search and you will see it is a highly regarded modification. Fuel Tank Vent Mod= fewer trips to the gas station.

 

And fewer boring drawn out top ups of the tank in freezing or scorching weather.

 

the label on side of cover says isb 325, next question vent mod can i do that or is it a dealer ship mod. and do i pay for it. will 4 inch exhaust help . or go to 5 inch? and what other mods our do i need? lol wife says none but you know will be pulling 8000 lbs trailer looking for mileage thanks matt

 

You have the 325/600 motor.

The vent mod is something you need to do yourself. I doubt the dealership would touch it or endorse it. It is actually very easy and the instructions are very well written.

Here is a link:

http://www.dodgedieseldatabase.com/david_kelley.htm

The 600 motor has a complete 4" exhaust system already. Most guys install some brand of flowthrough muffler in place of the factory muffler, or remove it and add a muffler delete pipe.

The 600 motor also has a catalytic converter. Some guys will pull the cat out as well. Since there is so little to be gained, and it violates Federal emissions regulations, I left my cat where it is.

There are the big 3 mods: Air intake system, exhaust, and some sort of programmer/box. You don't "need" any of it to pull that weight, but there are some benefits to them including: Cleaner air, better airflow, fuel economy improvements, lower egt's etc. All of which will improve your trucks towing performance. Don't forget the basic guages as well, turbo boost, egt, which some boxes such as the Juice/Attitude offer.

 

what about the electronic wastegate? that was not on the 305 motors. the 325/600 had the cat from the factory as well. but Justin has it correct, what does he know they only build them