u/Affectionate-Oil-883

I took what I believe to be a 350 turbo transmission I also took the ecu out of a 91 c2500 to put into my 94 c1500 it previously had a 4l60e and I quickly realized the wire harness is not matching the wire harness has a 13 pin connector and the wire connector for what I think is a 350 turbo is a 3 pin connector I’m curious if I can splice the 4l60 wire harness into the 3 pin connector? If possible how do I splice all those wires into a 3 wire connector?
I didn’t grab the wire harness from the truck with the 350 turbo and I’m trying to avoid finding one