The TREMEC's have a neutral start safety switch, backup light switch and electronic speedo pickup. You need to check your manual to make sure you wire the right connection.
IIRC though, the sensor sticking out the side with 2 prongs that look like small threaded bolt shafts is the backup light switch, the sensor towards the back with the female connector is the electric speedo hookup, and the wire dongle that hangs down is the neutral safety switch. That's on the TKO's at least, but I'm not 100% certain on that.
Who cares how much horsepower it has, all that matters is how fast it goes!
Untested 331, lots of suspension, chewing up corners.