The computer, intake manifold, wire harness attached to the intake manifold, fuse box under the hood, wire harness that runs along under the dash, fuse box under the dash, wire harness that runs up the drivers side of the engine bay, ignitor, coil, MAF sensor, and EVERYTHING under the hood that those wires plug to.  I'm not sure how it would be going from a 2nd gen to 2nd gen, but on my '81 where I used stuff from an '86, I stripped the dash/ left side of the engine bay harness down to five or seven wires, re-wrapped it, and grounded what needed to be grounded and gave power to what needed power.  I think I messed with a total of 12-15 wires.  In your case, it'll probably all plug into your existing plugs and whatnot.  My best advice would be to study the wiring diagrams from the two trucks, then compare the two harnesses and go from there.  It's not terribly complicated, but the different sources you get your info from will not all agree; the Pirate FAQ thread showed one pinout, Haynes showed another, the Toyota OEM showed yet a third, and my '86 harness didn't match any of those.  Be prepared for that.  If you can't trace wires and figure out what something is by using a multimeter to read resistance or voltage, or be able to tell what the sensor is by it's appearance and/ or location, you might want to have someone either do it for you or walk you through it in person.