I just got an 06 with the Hemi... love it. If you get it with the factory LSD, just be sure to maintain it. I am getting both diff fluids changed (synthetic).

 

I've got a '08 4X4 with the 4.7L and it runs great. But, the '08 4.7L is rated at 310hp, which is closer to the Hemi in hp. The older model 4.7L's are underpowered and I wouldn't even consider anything but a Hemi.

 

Lot of miles, towing occasionally, you are a prime candidate for a CTD! Now finding a fairly recent used one is gonna be the trick. Like 'Feej said, stay the hell away from the 07+ ones with the 6.7, unless you like to look a check engine lights (CELs) all the time. Emissions on the 6.7 is giving Chrysler/Cummins fits.

An 04.5 through 07 with the venerable old 5.9 CTD would be great, and will not suffer near the mpg loss while towing decent weight like any gas engine would. If you can find one that's not been beaten on and they ain't wanting you to take out a 2nd mtg. to get it, jump on one!

A good second choice would be a Hemi, great HP especially in the mid to upper rpm range and decent low end torque. Plus a lot of mods out there for it to get more low end power to the wheels for better towing. Also, it's gonna get the same to maybe 1 mpg less than the 4.7 at worst.

The pre '08 4.7 is a fantastic engine, durability wise, but so is the Hemi. But it's better suited in Jeep Grand Cherokee's and Dakota's. Would be a fine choice in a RCSB truck, especially a 4x2, but not suited well for a QC or 4x4 and especially out of it's element in a full size tow/haul truck...

 

all this hemi talk, i feel inadequate with my 4.7.....like my peter just just shrank

 

Only problem i see with the older CTD is the fuel. New fuel has had the sulfur cut down to almost nothing. 15 ppm. Older diesels without the heavy emissions crap run far better with old sulfur rich fuel. Basically, not the power is SHOULD have which = less milage etc...

 

I haven't noticed where the couple of guys I know with 5.9 CTD's are complaining about any felt power loss with the newer fuel and trust me, at least one guy would notice any loss of performance and bitch like hell.
Of course, if that's an issue you could always cheat. I won't name names, but I've got two separate friends in Ga. who go to the off-road/tractor pumps to fill their trucks. They been doing it forever, swear they get higher performance and it costs considerably less. Ain't neither one been caught yet...

 

Give the 4.7 some credit. My '02 4.7 QC's power is pretty good

 

or be even more different and get a 3.7 jk
you wont be disappointed with a hemi but if you dont need that extra power increase, you could just get a 4.7 which would be fine for cruising on the highway.

 

They arent getting higher performance...they are getting the performance their rigs SHOULD have. Off road fuel is not the degraded garbage at the pumps now, its the good ol stuff. I know its a bit different yet the same.
My semi lost 2 mpg overall average even with the 500 ppm fuel. Now that 500 ppm is getting phased out and all i can reall find is 15 ppm...my poor cummins n14 is suffering.

 

Well, last night I drove a '06 w/20k miles and Hemi, and tonight I drove a '08 Big Horn w/24k and 4.7. There is quite a difference. But do I need the difference......still unsure. I guess I would like to know about reliability of both, and MPG versus eachother. Again, I will be on the highway about 90% of my traveling. Thanks for the great input so far. BTW, LSD?