Weird swap?

Hey i need help! This is my first thread that im making. Anyway heres the story... I bought a 95 tacoma from a tow yard with a small "front bumper damage" online thinking i would save some money. Comes to my house few days ago and wont start. I pull out the sparks and the spark plugs dont have a spark even and i couldnt figure out why? (new spark plugs) so i had a experienced mechanic come by and he figured out that someone was swapping the engine and didnt finish the job. Its a 3.4 liter manual v6. When he took the glove compartment off he noticed the plugs to the computer werent even connected. Only 1 out of 4 were. So im thinking the engine harness doesnt match the computer, but then the interior dash harness did match. (the one plug). If anyone has any experience with these trucks please help and tell me what to do!