I have a 2003 ram 1500 quad cab with a 4.7 that self destructed(looks like it took a grenade)and of course I've had no luck finding a 4.7 under $2000 so I picked up a complete 5.7 hemi for $300 and I want to install it. I found a 2004 truck with a 5.7 that I can pull the entire wiring harness from. Is there any difference between the 2002 and 2004 wiring from the wiring in my 2003? I know the trans will bolt up. I can probably get the mounts from the same truck I'm getting the harness from. I guess the other things that might be different would be the radiator and the exhaust head pipes. Anything else I am missing ?

 

You might as well purchase the whole donor car as you might need many more parts than just the wiring harness.

There is a thread on the forums of someone doing a similar swap.. you will need a new computer for that vehicle as well.

Make sure you check that whole engine 100% for any problems before slapping it in there... b/c $300 Hemi engine seems very fishy to me.

 

Planning to rebuild the 5.7 before installing. I was going to have to build a 4.7 anyway so its really no more expensive. I found a 4.7 core but I can still build it for the 2003 Durango I have advertised for sale on the Dakota/Durango forum. I'm getting all the wiring and computors and everything from the donor vehicle but I don't forsee needing the whole thing besides the guy who has it wants to keep the motor.

 

I can't find the thread that had a completed swap done... might have been on another forum, but I remember it needed quite a few more parts than just the harness and computers...

 

16 page thread here https://dodgeforum.com/forum/3rd-gen...s-as-i-go.html
8 page thread here https://dodgeforum.com/forum/3rd-gen...003-5-7-a.html
https://dodgeforum.com/forum/3rd-gen...-a-hemi-2.html
I'd love to do that swap. But just getting to old to do that much wrenching and thinking. Good luck on the swap

 

Thanks for the links, I will be digging through them till I feel like I have a handle on this thing. I've been swapping engines since the 70's and it gets more complicated every year.

 

Find an engine wiring harness from a 2003 hemi truck. It will have the big C130 dash plug like your 2003 4.7 so you have very minimal wiring to do. Also get a pcm from a 2003.

You don't want a harness from an 04/05 unless you really want to hack it up or absolutely need to use a 04/05 pcm.

 

I'll bet you dropped a valve seat on that 4.7. Happened to me on the 4.7 HO in my old Grand Cherokee.

Was able to rebuild it pretty cheap though. Found a killer deal on an entire rebuild kit for around $800, all new pistons and everything. About $500 to have the heads rebuilt. After odds & ends (and about 30 hours labor on my part) I had the 4.7 rebuilt for just under $2000. But it was killer, compression dead on 190 on every cylinder.

But I'm with you on the Hemi replacement...