Casey,
Here's the way I'd write it up (feel free to use this or edit it to your liking), but I think anyone that has this part will know what you need with this discription.
"Wanted, 55-59 2-speed rear vacuum selector switch mounting bracket/cover. The bracket mounts to the top of the SM-420 transmission and holds the cable actuated switch in place."
Good Luck!
Mike B
