Help me buy the right truck!

[WilliamCotton]

Looking to buy a Dodge diesel, but can't decide weather to get a 5. 9 or a 6. 7.

Mainly interested in modifying it to get max milage, but avoiding maintenance headaches due the the mods.

Also, is the 6 speed a/t that much better than the 4 speed? I don't pull heavy loads.

Thanks for the comments. Bill

 

[HBarlow]

If your goal is to purchase a truck for the express purpose of modifying it I would not recommend the ISB6. 7 engines unless you plan to buy one that is out of warranty or you understand you will forfeit your warranty if modified. The ISB6. 7 is more complex and has more computerization which makes it less tolerant of modification.

The new six speed automatics are tremendously better than the old four speed 47 or 48REs but they are not suitable for modification either.

 

[firemansdiesel]

If this truck is going to be a fun/hobby truck that you want to mod. I would look at a '94-'98 12V CTD.

If it's going to be your daily driven truck then I would look at a '03-'07 5. 9 CTD. In those years w/ the 48re transmission. Eventually you will need to beef up the transmission just like any other vehicle you put TQ down more than stock. The 68rfe is limited to upgrades unlike the 48re, and the 68rfe is heck a lot more expensive to upgrade.

Stock for stock the 6 speed w/ exhaust brake and manual shifter paddle is better than a 4 speed in previuos years.

 

[WilliamCotton]

Harvey & James,
Thanks for the input. It helps! I'd love to own a daily driver that get 25mpg @ 55 if you keep your foot out of it. Think it's possible with a 5. 9 or a 12vCTV fixed up right?
Also, can you/has anybody put a 68rfe transmission in a 5. 9 truck? That sounds like the optimum set up?? Bill

 

[firemansdiesel]

I highly doubt you can install a 68rfe in a 5. 9 CTD. Too much electronics (PCM, ECM, etc. . ) The 25mpg most likely can be achieved in a 2 wheel drive 12V, and 4x4 around 20 mpg -/+... Mods = mpg does not happen all the time. The '03-'04 5. 9 CTD will be your best for mileage in the Common Rail. On average with 5. 9 Common Rail CTD your looking 15-19 mpg freeway unloaded.

Your best bet is look in the 2nd Gen Section (12V Engine and Transmission) and ask some questions about mileage and mods for the 12V.

 

[HBarlow]

Harvey & James,
Thanks for the input. It helps! I'd love to own a daily driver that get 25mpg @ 55 if you keep your foot out of it. Think it's possible with a 5. 9 or a 12vCTV fixed up right?
Also, can you/has anybody put a 68rfe transmission in a 5. 9 truck? That sounds like the optimum set up?? Bill

25mpg at a steady 55mph is not a big deal. Even some ISB6. 7s with a SmartyJr will probably approach that at a steady 55 assuming calm winds and level terrain.

The later trucks will retain clues in memory if a magic black box is added so that if you trash the engine and take it to a Dodge dealer expecting warranty repairs you'll be disappointed.

 

[CBlack]

Harvey & James,

Thanks for the input. It helps! I'd love to own a daily driver that get 25mpg @ 55 if you keep your foot out of it. Think it's possible with a 5. 9 or a 12vCTV fixed up right?

Also, can you/has anybody put a 68rfe transmission in a 5. 9 truck? That sounds like the optimum set up?? Bill

I'd put an Allison in over the 68rfe.



And the 6. 7 is great for modifying as long as you or the individual doing the work knows what they're doing.



Just remember... you pay to play.

 

[KLauber]

The best mileage I got on my 6. 7 unloaded was 24 MPG and that was due to hypermiling on the long downhill sections which is easy to do with a manual trans. Typically its 18 on the hwy and 15 stop and go. Towing cuts your mileage way down.

I'd get an 03 with a manual.

Good luck!

ken

 

[S.Morris]

With my sig truck, I can run a consistant 23mpg US. anytime I care to run a easy max of 55-60mph , with tonneau cover, in good weather conditions. Non 4x4 and non dually should be able to increase on this 10-20%.

 

[opmmotorsports]

Im running both, a 2007, 5. 9, 6spd. Std. daily driver, 2wd 4 door dually with MINOR mods.
I average mid to hi 20's
My 2011, 6. 7, 4wd, 6pd. Auto. 4dr. Dually. With just a cold air kit, on a GOOD DAY, same daily routes
Get maybe, 15. 5
Id go to another 06 or 07 in a flash if i could find a nice clean low miler to replace the 2011
Nic

 

[AABEN]

Stick with an 5/9 and you will not go wrong. GOOD LUCK

 

[AABEN]

Stick with the 5/9 and you will not go wrong. GOOD LUCK