ok here it is i have two rangers one is an 86 with a 2.3- 4 spark plug 4 cylinder and the other is an 89 with a 2.3- 8 spark plug 4 cylinder and heres th question do i absolutly have to change the wiring harness and the computer or just the comp what all needs to be done help please

 

Yes. Is the '86 carbed or fuel injected? Either way you will need the PCM and wiring harness from the '89 to run it. Other than that everything should pretty much fit into place, though the exhaust manifold might not swap over.

 

it is fuel injected and why wouldnt the exuast manifold swap or do you mean i wouldnt be able to take it off of my 86 and swap it to my 89 is that what you mean and would i have to have all of the wiring off of the driverside or just a few plugs please reply i am so lost on this project