Description This is a 91 350 TBI setup. Includes: intake & throttle body, fuel lines, distributor, coil, ignition wires, air cleaner, ecm, charcoal can, fuel lines & some misc. hoses + brackets, mounting bolts & wiring harness from auto trans First thing to do is lay it all out and inventory what you got. If you look close you will see that for a basic system I am missing 2 parts. 1. The CTS. 2. The O2 sensor. Connect all the parts onto the wiring harness. Most connectors are idiot proof and can only go 1 place..but there are exceptions so if your not sure, no problem, we will get to it soon! This is the ECM with the system. So what do we do first? Well we need to get rid of all that old covering and tape so we can trace the wires. A simple razor blade works fine, just don't cut into the wires! 15 min later... and this is what was removed so far. Now what do we want to do about this big thing???? Well there are a couple of options. 1. Leave it as is. If you pulled the system yourself then you could have saved the retaining clip. Then just cut a big hole in the firewall and stick it in. 2. Cut it out. You will eventually tailor the harness down to fit your IH anyway so just cut the whole harness in half and remove the plug out of it!! 3. Remove the plug from the wires.... There are a couple ways to do this. a. use heat(hot water/heat gun) to soften the outer case of the plug. Then pry the case off the outside. There are a couple little locks sticking thru one side that will need to be squeezed with some needle nose. Then you can use the needle nose to start pulling the goo off of the wires. tedious work. b. remove the outside case then use your heat gun to melt the goo off the wires. Hold it over a box or lined trashcan to catch all the drippings!! So now we need to determine which wires stay and which wires go!!! pinouts for ecm scroll down in the thread www.truckforum.org/forums/chevy-truck-forum/36278-electrical-diagrams-chevy-only-3.html Wiring Basics: 1. Most manufactures follow a basic wire color system. There will always be exceptions to the rule and a color may be used twice. There are also small difference from model/yr. But some colors to note are.... pink/blk-this is 12v that is from a switched source. red- 12v straight from the battery org- 12v after it goes thru a fuse or protection device. blk/wht- ground 2. Tie points shown on the diagrams will not be the physical location of the actual connection. A tie point can be any where along the same piece of wire and it will perform exactly the same! Lets start from the top.... First connector will be the small one that has an A side and a B side. Note the "A" and the numbers from 1-12 from right to left! And here is the larger C and D connector. Make sure you comb the wires out straight coming out of the connector so there are no mistaking which wire you are looking at. NOTE: You will not be using every wire that is in the plug. Because we are dealing with so many systems, make sure you use the wire listing and diagrams for your system. Some wire colors used will be different between different years. Just make sure that the designated pin goes to the listed location! Now starting with A1 we see it is Green with a white stripe and should go to the fuel pump relay. Follow the wire all the way to the end. Use your pen and masking tape and make a wire label!!! You may also want to put the name of the part it is hooked to. If the wire goes into a tie point with other wires I put a label there and at the end where it's going. Did you notice this system came with 2 bosch style relays instead of the older fuel pump relay!! Guess I won't need to buy a seperate power relay!!! Continue this thru the list.