What all will fit?
Sorry, read the reply and forgot to respond.
I'm no expert in this stuff, but here are my thoughts.
Here's the sticker. She does have the 45RFE.
So, if we keep that trans, the 5.7 will work better with the controller that's in the truck now?
Shocked it says what trans it has, but there it is.
Not saying a 5.7 would work better, only that it has a better chance of working with the wiring harness and that you will need something like it to maintain the TCM the trans needs. Not sure if there is a PCM that would work with a 2002 Dakota, that is the big unknown. Pretty sure there is an '04 PCM that might work with an '04 Dakota because the Hemi came out in '04. Pretty sure you have to be careful with matching the year of the truck to the PCM. Maybe not, but definitely something to research before pulling the trigger on anything. Could be that the '04 PCM for a 5.7 would work, but might not either.
So, if you want to keep the 45RFE, I think it has a better chance of succeeding if you keep the wiring harness, re-pin it as need to work with a Hemi PCM as needed and find a PCM that would work.
Will a trans from a 5.9 powered 1500-3500 work, or do I really want to get the 5.9 stuff (trans, harness) from a Durango ( more common than a 5.9 Dakota)? What else do we want to get out of the 5.9 powered vehicle?
Pretty sure you can get a 46RE trans out of just about anything and it would work. Far as I know they are all the same. You could also do a 42RE like is probably in the parts V6 Dakota. It would bolt up and run just like the 46RE would, and would even give you a deeper first gear. Biggest issue would be longevity as the 46RE is build to handle more torque.
I would guess you just need a wiring harness and PCM out of a 5.9 Durango. But you might have to start with that and see if anything else is required. I found several threads doing a Google search on "4.7 to 5.9 swap". But I have slept since then. :D
I figured that the 5.9 would be down on power and fuel economy vs the hemi in stock form. And I figured that either engine/ trans would have to be rebuilt. The rest of the stuff, rear end, gears, tubs, wouldn't really be cheaper one setup vs the other. So, in my reckoning, it looks like the 5.9 setup would be less costly than the Gen III installed, with similar power outputs.
It think the 5.9 would be the cheaper swap since it was kind of a factory option, just in the Durango and not in the Dakota. I think the 5.7 will put done more power and have greater potential, but not sure where the crossover line would be when the cost of doing the swap is added into the equation. Plenty of people are making big power with 408's in Dakota's so the 5.9 has it's place.
Something else to add in the mix is that as best I can remember the '04 Hemi PCM is not tunable, but the '05 is. And if the '04 PCM works in your '02 Dakota (still a big unknown), but the '05 PCM won't, then you will have to accept whatever power you are getting out of the 5.7 because you will be pretty much stuck. On the other hand, the 5.9 PCM can be tuned, of that I am certain.
Best I've got.
