kreigschnetzer

my dads transmission went out in his 91 mustang lx. i told him i would swap it since i was gonna rebuild it and he moved everything so i have no idea where it goes.

he was supposed to get a used transmission and was supposed to get the right one. I put the one in he got and it bolted up fine but one connector on the used trans only has two prongs and the connector on the 91 has three wires. i put it in because i was told that it matched and now i am hit with this.

So what i am getting at is do i have to swap trannys AGAIN or is there some modification to the plug.

Wire colors: 91- red, orange, black/yellow
89 red, orange

what does the black/yellow wire do and how can i fix my dilema?

i appreciate any help you can give me. thanks