I have an 02 Ram 1500 and am in the process of replacing the engine with a 5.7 Hemi out of an 05 Ram 1500. I have the harness for the new motor but it is different...I have two questions right now:

How do I take apart the junction box by the drivers side firewall on the 02 harness?
Will an 03 or 04 harness work with the 02 hookups in the truck?

 

Welcome to the site. There are more than a few threads on this. However it's not a cheap process.

 

If you can locate a rolled and totaled (but running) 5.7 for cheap it can be affordable!

Edit - I mean the whole chassis. Load the bastard on a trailer, pull off what you need, and send the rest to scrap to recoup a few hundos.