[slowmover]

06 2500 4x4, 5.9l turbo diesel, 2.5" lift in front to level, 4 spd auto 3.73 gears, 325/55r22 tires, intake, exhaust, programmer.

Lose the lift, re-establish front/rear rake, lose the programmer, lose the CAI, never threaten transmission life.

What is the weight rating of those tires & wheels? I cannot believe that they are a suitable match for a truck with a 9,000-lb GVWR. Stock size in MICHELIN AT2 would be a better choice, IMO. If underrated then this tells me that the truck is just a toy, as commercial haulers, ranchers, farmers, tradesmen, contractors, etc all have IRS-deductible miles. A truck not so outfitted is incapable of doing work, thus, will not be eligible by use (another vehicle would have sufficed); in a manner of speaking.

Maybe freewheeling front hub conversion at some point. A bed cover or close-fit bed cap, and a front spoiler is a recommendation found in plenty of places, and a partial or full removeable grille block might help (I may actually try this one).
If I was in the cold north, then I'd get the MOPAR winter front.

I run the highways at 1,725/50 rpm (58/9 mph GPS corrected) for best mileage. It falls off quickly above 60. Dropping below this isn't worth that much (although yesterday, driving coastal Lousiana at dead-on 1600 rpm I was seeing 29 mpg [corrected] for over 100 miles with a 5-mph quartering stern wind).

Otherwise I can highway trip plan for 24-mpg empty or loaded, cold/rainy or hot/clear, traffic or no traffic, day or night. Having a manual and 2WD is the real key to economy. I've seen 25 to 27 on a number of fillups.

Running 5-mph slow in town (and only accelerating up to 5-mph below that) works well, as does running roughly 10-mph slow on the big road. Set the cruise control at the end of the entrance ramp; never change lanes, maintain perfect lane center (honor all ramp speeds posted); signal all changes well in advance; plan all stops for food/fuel/rest in advance (trip plan); maintain a steady state as long as the truck (not driver) is capable.

You work for the truck, it does not work for you is how I see it.

Just change fluids/filters ahead of schedule, keep tires at DODGE recommended numbers. Far too many CTD owners are going over 100k on both oem tires and brakes. Any less is sign of poor driving, IMO. Almost needless to say is that a garaged vehicle will outlast a covered or exposed one.

Personally, I would never be turning a diesel on/off on the road.

Nor would I ever add unproven aftermarket tuners, bypass filters or other junk that does not add to or reinforce the 350,000 mile MTBO of a CTD. Buying a $16,000 long block is no more on my list than is a set of $3000 injectors. No aftermarket "economy" item is proven when it comes to drivetrain longevity so avoid them/lose them. Stick with FLEETGUARD or DONALDSON filtration.

You'll have enough problems with premature wear on balljoints and u-joints on a 4WD. Personally, I'd look at eliminating steering deadness on-center, adding polyurethane bushings to the anti-roll bar (and adding a rear one) and going with BILSTEIN shocks if I just had to spend money.

All things considered a perfectly stock CTD will outlast (cost less) than any modded one. One cannot have it both ways.

Sounds to me like you already have a pretty good handle on driving for economy. Focus on long-term reliability (and replace components before they wear out) is third. (Safety is first, these things ain't easy to stop).

Lowest cost per mile is the key. See EDMUNDS True Cost of Ownership and read through all links/info. You MUST reduce your cpm (not just fuel useage).