I am putting a 302 in my truck, getting rid of the dead 300, I know I have to do the engine mounts, radiator and fly wheel, but what has to be done for the wiring?!? Is it a simple swap of the engine harness and computer? It's the only set back I'm having.

 

Computer and engine harness stay with engine. Pull them and from the donor and put them in, it's relatively plug and play. If you've got different transmissions it could cause problems.

 

Yep. your tranny is AOD unless a manual. A ECU matched to an EAOD won't work in either case.