Ok, here's the deal, I have a 1988 camaro that I stripped down to bare metal (I'm mean everything off besides tires, brakes, etc.) only because mice got to it and thought everything was junk but the metal. Now, in place of the everythin a took out, I put in 1991 firebird stuff like the wiring (everything complete, not chopped up except the light harness cause switching to four headlights and the rear is different) and the interior, engine wiring (which is for the 1991 firebird L03) and computer(1228746). My question is, I have a 89 or 90 truck L05( that is complete with the harness for that motor still attached and ECM 1227747) that I'm wanting to put in, so could I just put the motor in and use the 305 harness and take the prom out of the 1227747 and put it in the 1228746? or just use the 1227747 ecm? or do I have to use the wiring harness and computer for the L05? Now looking at the L05 wiring harness I notice that there are some other connectors close to the connection by the ECM that would not plug in at all and the two that would have different wiring on one end (they would plug in but for example one color wire might be brown and the one it meets up with is white, and there are not even wires where there should be in the connectors themselves). I know that the options on a firebird and a truck are different but my main concern is that something is not going to be working right if I use the L05 truck harness. Anyone with any advice would be greatly appreciated. Thanks!

I did that too, put a 95 L05 from a truck in my 89 camaro in place of the 305 TBI. The entire wiring harness that was in the car hooks up to motor. I reused the intake and the TBI for wiring connecting reasons. Everything hooked up and i used the existing computer. I ended up having to tune the computer myself to get it to run right. But i did that with all the original wiring and computer. Read through the "Come in for a free tune" sticky at the top of main TBI page.