You have the auto harness already. It has the correct connector on it.
Take any m5od harness you can find and splice it into the correct (the one you already have) connector.
The wiring going to the m5 will be the same on the older ones, its just the connector thats different. The only difference you will find is some m5 transmissions will have just the reverse switch and some will have the reverse switch and neutral switch.
Your making a mountain out of a mole hill Tammy. My 94 limited still has the auto harness in it. I just spliced the neutral safety wires into the neutral switch (It will ONLY crank in neutral this way. Planned it that way for remote start.) and the reverse light plug spliced in. It took all of 10 minutes to modify the harness, and that was taking the time to solder and heat shrink the wires.