[StealthDiesel]

Well, my 2wd 3rd gen is lowered 1 inch up front and 3 inches in the rear and I get worse fuel economy than anyone on this forum!

I don't think any aero changes are going to make much difference.
However, lowering the front of these trucks, to get the heavy Cummins lower, will make a terrible handling truck, handle a little better.


There were several threads where folks were installing the deeper late Superduty front air dam on their Dodge trucks trying to improve aero and fuel economy.
It was a simple bolt on but I'm sure it did not make one bit of difference though!

 

[StealthDiesel]

I really dont think the rubber seals are worth it at all but I would recommend to install clear film paint protection to protect the paint where the rubber seals will touch.

To prevent the rubber seals from wearing off the paint and then rust starting.

You can purchase clear film paint protection in rolls of various widths.

 

[StealthDiesel]

Bump because subtle aero mods are good for small gains in mpg... plus you new guys need something else to read

^^ LOL.

I didn't re-read this entire thread but have you ever considered lowering your 2500 4wd for further MPG gains?
I don't think you are towing much nor hauling tons nor going off-road?
Trim the front coils for a 1 inch drop, remove the rear spacer blocks, re-arch rear leaf springs.
Plus lowering the truck and Cummins center of gravity will improve handling.

My 2wd is lowered 1 inch in the front, 2 inches in the rear. Just for better handling and to improve the stance.
I would love to lower it more but there is no good way to further lower the front without messing up the geometry.
Lowering the rear further would require a simple frame C-notch.

Just a thought..

 

[StealthDiesel]

Years ago guys were installing the larger Ford Superduty front air dam (under the front bumper) on the 3rd Gens.
It was cheap and easy bolt on.

Perhaps you already investigated this or something similar?