That helps me out. Going back to your first post, you will need the computer and all of its wiring harness, components, etc... to run everything including the motor. But ya I think you can put a 4.0 liter in the truck with on problems. But the fuel pressure needed for the 4.0 liter is greater then that of an 86 fuel pump can put out. From what I've read the 86 fuel pump puts out 44psi and the explorer fuel pump puts out 75-90 psi.