A couple months ago, I bought a 1992 G30 Vandura that was converted to a short school bus. It had a bad transmission, so I bought a "used but good" 4L80 from Facebook Marketplace. After installing it, I've discovered it has a different connector plug on the side of the transmission than the one that my bus has on the wiring harness, my bus apparently has what is known as the "old style" harness, and the new transmission has the "updated style" connector. I bought a pigtail harness, thinking I could just wire it in, but after doing so I found that the new pigtail has 11 wires, and my current harness has 12 wires in it.
So my question is really if this wiring conversion can even be done, or do I need to go find a transmission with the proper connector?
I also discovered that the transmission I bought has a completely different output shaft, so the transmission needs to come back out anyways. If the wiring harness can be converted, I will swap in my old output shaft, but if it can't, I'll likely just sell the transmission back to the Marketplace.

Thank you in advance for your help!